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[Linux-stable-mirror] [patch 101/114] pipe: fix off-by-one error when checking buffer limits

by akpm＠linux-foundation.org

From: Eric Biggers <ebiggers(a)google.com> Subject: pipe: fix off-by-one error when checking buffer limits With pipe-user-pages-hard set to 'N', users were actually only allowed up to 'N - 1' buffers; and likewise for pipe-user-pages-soft. Fix this to allow up to 'N' buffers, as would be expected. Link: http://lkml.kernel.org/r/20180111052902.14409-5-ebiggers3@gmail.com Fixes: b0b91d18e2e9 ("pipe: fix limit checking in pipe_set_size()") Signed-off-by: Eric Biggers <ebiggers(a)google.com> Acked-by: Willy Tarreau <w(a)1wt.eu> Acked-by: Kees Cook <keescook(a)chromium.org> Acked-by: Joe Lawrence <joe.lawrence(a)redhat.com> Cc: Alexander Viro <viro(a)zeniv.linux.org.uk> Cc: "Luis R . Rodriguez" <mcgrof(a)kernel.org> Cc: Michael Kerrisk <mtk.manpages(a)gmail.com> Cc: Mikulas Patocka <mpatocka(a)redhat.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- fs/pipe.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff -puN fs/pipe.c~pipe-fix-off-by-one-error-when-checking-buffer-limits fs/pipe.c --- a/fs/pipe.c~pipe-fix-off-by-one-error-when-checking-buffer-limits +++ a/fs/pipe.c @@ -605,12 +605,12 @@ static unsigned long account_pipe_buffer static bool too_many_pipe_buffers_soft(unsigned long user_bufs) { - return pipe_user_pages_soft && user_bufs >= pipe_user_pages_soft; + return pipe_user_pages_soft && user_bufs > pipe_user_pages_soft; } static bool too_many_pipe_buffers_hard(unsigned long user_bufs) { - return pipe_user_pages_hard && user_bufs >= pipe_user_pages_hard; + return pipe_user_pages_hard && user_bufs > pipe_user_pages_hard; } static bool is_unprivileged_user(void) _

7 years, 4 months

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[Linux-stable-mirror] [patch 100/114] pipe: actually allow root to exceed the pipe buffer limits

by akpm＠linux-foundation.org

From: Eric Biggers <ebiggers(a)google.com> Subject: pipe: actually allow root to exceed the pipe buffer limits pipe-user-pages-hard and pipe-user-pages-soft are only supposed to apply to unprivileged users, as documented in both Documentation/sysctl/fs.txt and the pipe(7) man page. However, the capabilities are actually only checked when increasing a pipe's size using F_SETPIPE_SZ, not when creating a new pipe. Therefore, if pipe-user-pages-hard has been set, the root user can run into it and be unable to create pipes. Similarly, if pipe-user-pages-soft has been set, the root user can run into it and have their pipes limited to 1 page each. Fix this by allowing the privileged override in both cases. Link: http://lkml.kernel.org/r/20180111052902.14409-4-ebiggers3@gmail.com Fixes: 759c01142a5d ("pipe: limit the per-user amount of pages allocated in pipes") Signed-off-by: Eric Biggers <ebiggers(a)google.com> Acked-by: Kees Cook <keescook(a)chromium.org> Acked-by: Joe Lawrence <joe.lawrence(a)redhat.com> Cc: Alexander Viro <viro(a)zeniv.linux.org.uk> Cc: "Luis R . Rodriguez" <mcgrof(a)kernel.org> Cc: Michael Kerrisk <mtk.manpages(a)gmail.com> Cc: Mikulas Patocka <mpatocka(a)redhat.com> Cc: Willy Tarreau <w(a)1wt.eu> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- fs/pipe.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff -puN fs/pipe.c~pipe-actually-allow-root-to-exceed-the-pipe-buffer-limits fs/pipe.c --- a/fs/pipe.c~pipe-actually-allow-root-to-exceed-the-pipe-buffer-limits +++ a/fs/pipe.c @@ -613,6 +613,11 @@ static bool too_many_pipe_buffers_hard(u return pipe_user_pages_hard && user_bufs >= pipe_user_pages_hard; } +static bool is_unprivileged_user(void) +{ + return !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN); +} + struct pipe_inode_info *alloc_pipe_info(void) { struct pipe_inode_info *pipe; @@ -629,12 +634,12 @@ struct pipe_inode_info *alloc_pipe_info( user_bufs = account_pipe_buffers(user, 0, pipe_bufs); - if (too_many_pipe_buffers_soft(user_bufs)) { + if (too_many_pipe_buffers_soft(user_bufs) && is_unprivileged_user()) { user_bufs = account_pipe_buffers(user, pipe_bufs, 1); pipe_bufs = 1; } - if (too_many_pipe_buffers_hard(user_bufs)) + if (too_many_pipe_buffers_hard(user_bufs) && is_unprivileged_user()) goto out_revert_acct; pipe->bufs = kcalloc(pipe_bufs, sizeof(struct pipe_buffer), @@ -1065,7 +1070,7 @@ static long pipe_set_size(struct pipe_in if (nr_pages > pipe->buffers && (too_many_pipe_buffers_hard(user_bufs) || too_many_pipe_buffers_soft(user_bufs)) && - !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) { + is_unprivileged_user()) { ret = -EPERM; goto out_revert_acct; } _

7 years, 4 months

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[Linux-stable-mirror] [patch 097/114] kasan: rework Kconfig settings

by akpm＠linux-foundation.org

From: Arnd Bergmann <arnd(a)arndb.de> Subject: kasan: rework Kconfig settings We get a lot of very large stack frames using gcc-7.0.1 with the default -fsanitize-address-use-after-scope --param asan-stack=1 options, which can easily cause an overflow of the kernel stack, e.g. drivers/gpu/drm/i915/gvt/handlers.c:2434:1: warning: the frame size of 46176 bytes is larger than 3072 bytes drivers/net/wireless/ralink/rt2x00/rt2800lib.c:5650:1: warning: the frame size of 23632 bytes is larger than 3072 bytes lib/atomic64_test.c:250:1: warning: the frame size of 11200 bytes is larger than 3072 bytes drivers/gpu/drm/i915/gvt/handlers.c:2621:1: warning: the frame size of 9208 bytes is larger than 3072 bytes drivers/media/dvb-frontends/stv090x.c:3431:1: warning: the frame size of 6816 bytes is larger than 3072 bytes fs/fscache/stats.c:287:1: warning: the frame size of 6536 bytes is larger than 3072 bytes To reduce this risk, -fsanitize-address-use-after-scope is now split out into a separate CONFIG_KASAN_EXTRA Kconfig option, leading to stack frames that are smaller than 2 kilobytes most of the time on x86_64. An earlier version of this patch also prevented combining KASAN_EXTRA with KASAN_INLINE, but that is no longer necessary with gcc-7.0.1. All patches to get the frame size below 2048 bytes with CONFIG_KASAN=y and CONFIG_KASAN_EXTRA=n have been merged by maintainers now, so we can bring back that default now. KASAN_EXTRA=y still causes lots of warnings but now defaults to !COMPILE_TEST to disable it in allmodconfig, and it remains disabled in all other defconfigs since it is a new option. I arbitrarily raise the warning limit for KASAN_EXTRA to 3072 to reduce the noise, but an allmodconfig kernel still has around 50 warnings on gcc-7. I experimented a bit more with smaller stack frames and have another follow-up series that reduces the warning limit for 64-bit architectures to 1280 bytes (without CONFIG_KASAN). With earlier versions of this patch series, I also had patches to address the warnings we get with KASAN and/or KASAN_EXTRA, using a "noinline_if_stackbloat" annotation. That annotation now got replaced with a gcc-8 bugfix (see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715) and a workaround for older compilers, which means that KASAN_EXTRA is now just as bad as before and will lead to an instant stack overflow in a few extreme cases. This reverts parts of commit commit 3f181b4 ("lib/Kconfig.debug: disable -Wframe-larger-than warnings with KASAN=y"). Two patches in linux-next should be merged first to avoid introducing warnings in an allmodconfig build: 3cd890dbe2a4 ("media: dvb-frontends: fix i2c access helpers for KASAN") 16c3ada89cff ("media: r820t: fix r820t_write_reg for KASAN") Do we really need to backport this? I think we do: without this patch, enabling KASAN will lead to unavoidable kernel stack overflow in certain device drivers when built with gcc-7 or higher on linux-4.10+ or any version that contains a backport of commit c5caf21ab0cf8. Most people are probably still on older compilers, but it will get worse over time as they upgrade their distros. The warnings we get on kernels older than this should all be for code that uses dangerously large stack frames, though most of them do not cause an actual stack overflow by themselves.The asan-stack option was added in linux-4.0, and commit 3f181b4d8652 ("lib/Kconfig.debug: disable -Wframe-larger-than warnings with KASAN=y") effectively turned off the warning for allmodconfig kernels, so I would like to see this fix backported to any kernels later than 4.0. I have done dozens of fixes for individual functions with stack frames larger than 2048 bytes with asan-stack, and I plan to make sure that all those fixes make it into the stable kernels as well (most are already there). Part of the complication here is that asan-stack (from 4.0) was originally assumed to always require much larger stacks, but that turned out to be a combination of multiple gcc bugs that we have now worked around and fixed, but sanitize-address-use-after-scope (from v4.10) has a much higher inherent stack usage and also suffers from at least three other problems that we have analyzed but not yet fixed upstream, each of them makes the stack usage more severe than it should be. Link: http://lkml.kernel.org/r/20171221134744.2295529-1-arnd@arndb.de Signed-off-by: Arnd Bergmann <arnd(a)arndb.de> Acked-by: Andrey Ryabinin <aryabinin(a)virtuozzo.com> Cc: Mauro Carvalho Chehab <mchehab(a)kernel.org> Cc: Andrey Ryabinin <aryabinin(a)virtuozzo.com> Cc: Alexander Potapenko <glider(a)google.com> Cc: Dmitry Vyukov <dvyukov(a)google.com> Cc: Andrey Konovalov <andreyknvl(a)google.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- lib/Kconfig.debug | 2 +- lib/Kconfig.kasan | 11 +++++++++++ scripts/Makefile.kasan | 2 ++ 3 files changed, 14 insertions(+), 1 deletion(-) diff -puN lib/Kconfig.debug~kasan-rework-kconfig-settings lib/Kconfig.debug --- a/lib/Kconfig.debug~kasan-rework-kconfig-settings +++ a/lib/Kconfig.debug @@ -217,7 +217,7 @@ config ENABLE_MUST_CHECK config FRAME_WARN int "Warn for stack frames larger than (needs gcc 4.4)" range 0 8192 - default 0 if KASAN + default 3072 if KASAN_EXTRA default 2048 if GCC_PLUGIN_LATENT_ENTROPY default 1280 if (!64BIT && PARISC) default 1024 if (!64BIT && !PARISC) diff -puN lib/Kconfig.kasan~kasan-rework-kconfig-settings lib/Kconfig.kasan --- a/lib/Kconfig.kasan~kasan-rework-kconfig-settings +++ a/lib/Kconfig.kasan @@ -20,6 +20,17 @@ config KASAN Currently CONFIG_KASAN doesn't work with CONFIG_DEBUG_SLAB (the resulting kernel does not boot). +config KASAN_EXTRA + bool "KAsan: extra checks" + depends on KASAN && DEBUG_KERNEL && !COMPILE_TEST + help + This enables further checks in the kernel address sanitizer, for now + it only includes the address-use-after-scope check that can lead + to excessive kernel stack usage, frame size warnings and longer + compile time. + https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715 has more + + choice prompt "Instrumentation type" depends on KASAN diff -puN scripts/Makefile.kasan~kasan-rework-kconfig-settings scripts/Makefile.kasan --- a/scripts/Makefile.kasan~kasan-rework-kconfig-settings +++ a/scripts/Makefile.kasan @@ -38,7 +38,9 @@ else endif +ifdef CONFIG_KASAN_EXTRA CFLAGS_KASAN += $(call cc-option, -fsanitize-address-use-after-scope) +endif CFLAGS_KASAN_NOSANITIZE := -fno-builtin _

7 years, 4 months

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[Linux-stable-mirror] [patch 080/114] lib/ubsan: add type mismatch handler for new GCC/Clang

by akpm＠linux-foundation.org

From: Andrey Ryabinin <aryabinin(a)virtuozzo.com> Subject: lib/ubsan: add type mismatch handler for new GCC/Clang UBSAN=y fails to build with new GCC/clang: arch/x86/kernel/head64.o: In function `sanitize_boot_params': arch/x86/include/asm/bootparam_utils.h:37: undefined reference to `__ubsan_handle_type_mismatch_v1' because Clang and GCC 8 slightly changed ABI for 'type mismatch' errors. Compiler now uses new __ubsan_handle_type_mismatch_v1() function with slightly modified 'struct type_mismatch_data'. Let's add new 'struct type_mismatch_data_common' which is independent from compiler's layout of 'struct type_mismatch_data'. And make __ubsan_handle_type_mismatch[_v1]() functions transform compiler-dependent type mismatch data to our internal representation. This way, we can support both old and new compilers with minimal amount of change. Link: http://lkml.kernel.org/r/20180119152853.16806-1-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin(a)virtuozzo.com> Reported-by: Sodagudi Prasad <psodagud(a)codeaurora.org> Cc: <stable(a)vger.kernel.org> [4.5+] Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- lib/ubsan.c | 48 ++++++++++++++++++++++++++++++++++++++---------- lib/ubsan.h | 14 ++++++++++++++ 2 files changed, 52 insertions(+), 10 deletions(-) diff -puN lib/ubsan.c~lib-ubsan-add-type-mismatch-handler-for-new-gcc-clang lib/ubsan.c --- a/lib/ubsan.c~lib-ubsan-add-type-mismatch-handler-for-new-gcc-clang +++ a/lib/ubsan.c @@ -265,14 +265,14 @@ void __ubsan_handle_divrem_overflow(stru } EXPORT_SYMBOL(__ubsan_handle_divrem_overflow); -static void handle_null_ptr_deref(struct type_mismatch_data *data) +static void handle_null_ptr_deref(struct type_mismatch_data_common *data) { unsigned long flags; - if (suppress_report(&data->location)) + if (suppress_report(data->location)) return; - ubsan_prologue(&data->location, &flags); + ubsan_prologue(data->location, &flags); pr_err("%s null pointer of type %s\n", type_check_kinds[data->type_check_kind], @@ -281,15 +281,15 @@ static void handle_null_ptr_deref(struct ubsan_epilogue(&flags); } -static void handle_misaligned_access(struct type_mismatch_data *data, +static void handle_misaligned_access(struct type_mismatch_data_common *data, unsigned long ptr) { unsigned long flags; - if (suppress_report(&data->location)) + if (suppress_report(data->location)) return; - ubsan_prologue(&data->location, &flags); + ubsan_prologue(data->location, &flags); pr_err("%s misaligned address %p for type %s\n", type_check_kinds[data->type_check_kind], @@ -299,15 +299,15 @@ static void handle_misaligned_access(str ubsan_epilogue(&flags); } -static void handle_object_size_mismatch(struct type_mismatch_data *data, +static void handle_object_size_mismatch(struct type_mismatch_data_common *data, unsigned long ptr) { unsigned long flags; - if (suppress_report(&data->location)) + if (suppress_report(data->location)) return; - ubsan_prologue(&data->location, &flags); + ubsan_prologue(data->location, &flags); pr_err("%s address %p with insufficient space\n", type_check_kinds[data->type_check_kind], (void *) ptr); @@ -315,7 +315,7 @@ static void handle_object_size_mismatch( ubsan_epilogue(&flags); } -void __ubsan_handle_type_mismatch(struct type_mismatch_data *data, +static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data, unsigned long ptr) { @@ -326,8 +326,36 @@ void __ubsan_handle_type_mismatch(struct else handle_object_size_mismatch(data, ptr); } + +void __ubsan_handle_type_mismatch(struct type_mismatch_data *data, + unsigned long ptr) +{ + struct type_mismatch_data_common common_data = { + .location = &data->location, + .type = data->type, + .alignment = data->alignment, + .type_check_kind = data->type_check_kind + }; + + ubsan_type_mismatch_common(&common_data, ptr); +} EXPORT_SYMBOL(__ubsan_handle_type_mismatch); +void __ubsan_handle_type_mismatch_v1(struct type_mismatch_data_v1 *data, + unsigned long ptr) +{ + + struct type_mismatch_data_common common_data = { + .location = &data->location, + .type = data->type, + .alignment = 1UL << data->log_alignment, + .type_check_kind = data->type_check_kind + }; + + ubsan_type_mismatch_common(&common_data, ptr); +} +EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1); + void __ubsan_handle_nonnull_return(struct nonnull_return_data *data) { unsigned long flags; diff -puN lib/ubsan.h~lib-ubsan-add-type-mismatch-handler-for-new-gcc-clang lib/ubsan.h --- a/lib/ubsan.h~lib-ubsan-add-type-mismatch-handler-for-new-gcc-clang +++ a/lib/ubsan.h @@ -37,6 +37,20 @@ struct type_mismatch_data { unsigned char type_check_kind; }; +struct type_mismatch_data_v1 { + struct source_location location; + struct type_descriptor *type; + unsigned char log_alignment; + unsigned char type_check_kind; +}; + +struct type_mismatch_data_common { + struct source_location *location; + struct type_descriptor *type; + unsigned long alignment; + unsigned char type_check_kind; +}; + struct nonnull_arg_data { struct source_location location; struct source_location attr_location; _

7 years, 4 months

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[Linux-stable-mirror] [patch 075/114] kernel/relay.c: revert "kernel/relay.c: fix potential memory leak"

by akpm＠linux-foundation.org

From: Eric Biggers <ebiggers(a)google.com> Subject: kernel/relay.c: revert "kernel/relay.c: fix potential memory leak" This reverts ba62bafe942b159a6 ("kernel/relay.c: fix potential memory leak"). This commit introduced a double free bug, because 'chan' is already freed by the line: kref_put(&chan->kref, relay_destroy_channel); This bug was found by syzkaller, using the BLKTRACESETUP ioctl. Link: http://lkml.kernel.org/r/20180127004759.101823-1-ebiggers3@gmail.com Fixes: ba62bafe942b ("kernel/relay.c: fix potential memory leak") Signed-off-by: Eric Biggers <ebiggers(a)google.com> Reported-by: syzbot <syzkaller(a)googlegroups.com> Reviewed-by: Andrew Morton <akpm(a)linux-foundation.org> Cc: Zhouyi Zhou <yizhouzhou(a)ict.ac.cn> Cc: Jens Axboe <axboe(a)kernel.dk> Cc: <stable(a)vger.kernel.org> [4.7+] Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- kernel/relay.c | 1 - 1 file changed, 1 deletion(-) diff -puN kernel/relay.c~revert-kernel-relayc-fix-potential-memory-leak kernel/relay.c --- a/kernel/relay.c~revert-kernel-relayc-fix-potential-memory-leak +++ a/kernel/relay.c @@ -611,7 +611,6 @@ free_bufs: kref_put(&chan->kref, relay_destroy_channel); mutex_unlock(&relay_channels_mutex); - kfree(chan); return NULL; } EXPORT_SYMBOL_GPL(relay_open); _

7 years, 4 months

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[Linux-stable-mirror] [patch 033/114] kernel/async.c: revert "async: simplify lowest_in_progress()"

by akpm＠linux-foundation.org

From: Rasmus Villemoes <linux(a)rasmusvillemoes.dk> Subject: kernel/async.c: revert "async: simplify lowest_in_progress()" This reverts 92266d6ef60c2381 ("async: simplify lowest_in_progress()"), which was simply wrong: In the case where domain is NULL, we now use the wrong offsetof() in the list_first_entry macro, so we don't actually fetch the ->cookie value, but rather the eight bytes located sizeof(struct list_head) further into the struct async_entry. On 64 bit, that's the data member, while on 32 bit, that's a u64 built from func and data in some order. I think the bug happens to be harmless in practice: It obviously only affects callers which pass a NULL domain, and AFAICT the only such caller is async_synchronize_full() -> async_synchronize_full_domain(NULL) -> async_synchronize_cookie_domain(ASYNC_COOKIE_MAX, NULL) and the ASYNC_COOKIE_MAX means that in practice we end up waiting for the async_global_pending list to be empty - but it would break if somebody happened to pass (void*)-1 as the data element to async_schedule, and of course also if somebody ever does a async_synchronize_cookie_domain(, NULL) with a "finite" cookie value. Maybe the "harmless in practice" means this isn't -stable material. But I'm not completely confident my quick git grep'ing is enough, and there might be affected code in one of the earlier kernels that has since been removed, so I'll leave the decision to the stable guys. Link: http://lkml.kernel.org/r/20171128104938.3921-1-linux@rasmusvillemoes.dk Fixes: 92266d6ef60c "async: simplify lowest_in_progress()" Signed-off-by: Rasmus Villemoes <linux(a)rasmusvillemoes.dk> Acked-by: Tejun Heo <tj(a)kernel.org> Cc: Arjan van de Ven <arjan(a)linux.intel.com> Cc: Adam Wallis <awallis(a)codeaurora.org> Cc: Lai Jiangshan <laijs(a)cn.fujitsu.com> Cc: <stable(a)vger.kernel.org> [3.10+] Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- kernel/async.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff -puN kernel/async.c~revert-async-simplify-lowest_in_progress kernel/async.c --- a/kernel/async.c~revert-async-simplify-lowest_in_progress +++ a/kernel/async.c @@ -84,20 +84,24 @@ static atomic_t entry_count; static async_cookie_t lowest_in_progress(struct async_domain *domain) { - struct list_head *pending; + struct async_entry *first = NULL; async_cookie_t ret = ASYNC_COOKIE_MAX; unsigned long flags; spin_lock_irqsave(&async_lock, flags); - if (domain) - pending = &domain->pending; - else - pending = &async_global_pending; + if (domain) { + if (!list_empty(&domain->pending)) + first = list_first_entry(&domain->pending, + struct async_entry, domain_list); + } else { + if (!list_empty(&async_global_pending)) + first = list_first_entry(&async_global_pending, + struct async_entry, global_list); + } - if (!list_empty(pending)) - ret = list_first_entry(pending, struct async_entry, - domain_list)->cookie; + if (first) + ret = first->cookie; spin_unlock_irqrestore(&async_lock, flags); return ret; _

7 years, 4 months

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[Linux-stable-mirror] [patch 021/114] fs/proc/kcore.c: use probe_kernel_read() instead of memcpy()

by akpm＠linux-foundation.org

From: Heiko Carstens <heiko.carstens(a)de.ibm.com> Subject: fs/proc/kcore.c: use probe_kernel_read() instead of memcpy() df04abfd181a ("fs/proc/kcore.c: Add bounce buffer for ktext data") added a bounce buffer to avoid hardened usercopy checks. Copying to the bounce buffer was implemented with a simple memcpy() assuming that it is always valid to read from kernel memory iff the kern_addr_valid() check passed. A simple, but pointless, test case like "dd if=/proc/kcore of=/dev/null" now can easily crash the kernel, since the former execption handling on invalid kernel addresses now doesn't work anymore. Also adding a kern_addr_valid() implementation wouldn't help here. Most architectures simply return 1 here, while a couple implemented a page table walk to figure out if something is mapped at the address in question. With DEBUG_PAGEALLOC active mappings are established and removed all the time, so that relying on the result of kern_addr_valid() before executing the memcpy() also doesn't work. Therefore simply use probe_kernel_read() to copy to the bounce buffer. This also allows to simplify read_kcore(). At least on s390 this fixes the observed crashes and doesn't introduce warnings that were removed with df04abfd181a ("fs/proc/kcore.c: Add bounce buffer for ktext data"), even though the generic probe_kernel_read() implementation uses uaccess functions. While looking into this I'm also wondering if kern_addr_valid() could be completely removed...(?) Link: http://lkml.kernel.org/r/20171202132739.99971-1-heiko.carstens@de.ibm.com Fixes: df04abfd181a ("fs/proc/kcore.c: Add bounce buffer for ktext data") Fixes: f5509cc18daa ("mm: Hardened usercopy") Signed-off-by: Heiko Carstens <heiko.carstens(a)de.ibm.com> Acked-by: Kees Cook <keescook(a)chromium.org> Cc: Jiri Olsa <jolsa(a)kernel.org> Cc: Al Viro <viro(a)ZenIV.linux.org.uk> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- fs/proc/kcore.c | 18 +++++------------- 1 file changed, 5 insertions(+), 13 deletions(-) diff -puN fs/proc/kcore.c~fs-proc-kcorec-use-probe_kernel_read-instead-of-memcpy fs/proc/kcore.c --- a/fs/proc/kcore.c~fs-proc-kcorec-use-probe_kernel_read-instead-of-memcpy +++ a/fs/proc/kcore.c @@ -512,23 +512,15 @@ read_kcore(struct file *file, char __use return -EFAULT; } else { if (kern_addr_valid(start)) { - unsigned long n; - /* * Using bounce buffer to bypass the * hardened user copy kernel text checks. */ - memcpy(buf, (char *) start, tsz); - n = copy_to_user(buffer, buf, tsz); - /* - * We cannot distinguish between fault on source - * and fault on destination. When this happens - * we clear too and hope it will trigger the - * EFAULT again. - */ - if (n) { - if (clear_user(buffer + tsz - n, - n)) + if (probe_kernel_read(buf, (void *) start, tsz)) { + if (clear_user(buffer, tsz)) + return -EFAULT; + } else { + if (copy_to_user(buffer, buf, tsz)) return -EFAULT; } } else { _

7 years, 4 months

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[Linux-stable-mirror] [patch 001/114] kasan: don't emit builtin calls when sanitization is off

by akpm＠linux-foundation.org

From: Andrey Konovalov <andreyknvl(a)google.com> Subject: kasan: don't emit builtin calls when sanitization is off With KASAN enabled the kernel has two different memset() functions, one with KASAN checks (memset) and one without (__memset). KASAN uses some macro tricks to use the proper version where required. For example memset() calls in mm/slub.c are without KASAN checks, since they operate on poisoned slab object metadata. The issue is that clang emits memset() calls even when there is no memset() in the source code. They get linked with improper memset() implementation and the kernel fails to boot due to a huge amount of KASAN reports during early boot stages. The solution is to add -fno-builtin flag for files with KASAN_SANITIZE := n marker. Link: http://lkml.kernel.org/r/8ffecfffe04088c52c42b92739c2bd8a0bcb3f5e.151638459… Signed-off-by: Andrey Konovalov <andreyknvl(a)google.com> Acked-by: Nick Desaulniers <ndesaulniers(a)google.com> Cc: Masahiro Yamada <yamada.masahiro(a)socionext.com> Cc: Michal Marek <michal.lkml(a)markovi.net> Cc: Andrey Ryabinin <aryabinin(a)virtuozzo.com> Cc: Alexander Potapenko <glider(a)google.com> Cc: Dmitry Vyukov <dvyukov(a)google.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- Makefile | 3 ++- scripts/Makefile.kasan | 3 +++ scripts/Makefile.lib | 2 +- 3 files changed, 6 insertions(+), 2 deletions(-) diff -puN Makefile~kasan-dont-emit-builtin-calls-when-sanitization-is-off Makefile --- a/Makefile~kasan-dont-emit-builtin-calls-when-sanitization-is-off +++ a/Makefile @@ -434,7 +434,8 @@ export MAKE LEX YACC AWK GENKSYMS INSTAL export HOSTCXX HOSTCXXFLAGS LDFLAGS_MODULE CHECK CHECKFLAGS export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS LDFLAGS -export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE CFLAGS_KASAN CFLAGS_UBSAN +export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE +export CFLAGS_KASAN CFLAGS_KASAN_NOSANITIZE CFLAGS_UBSAN export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL diff -puN scripts/Makefile.kasan~kasan-dont-emit-builtin-calls-when-sanitization-is-off scripts/Makefile.kasan --- a/scripts/Makefile.kasan~kasan-dont-emit-builtin-calls-when-sanitization-is-off +++ a/scripts/Makefile.kasan @@ -31,4 +31,7 @@ else endif CFLAGS_KASAN += $(call cc-option, -fsanitize-address-use-after-scope) + +CFLAGS_KASAN_NOSANITIZE := -fno-builtin + endif diff -puN scripts/Makefile.lib~kasan-dont-emit-builtin-calls-when-sanitization-is-off scripts/Makefile.lib --- a/scripts/Makefile.lib~kasan-dont-emit-builtin-calls-when-sanitization-is-off +++ a/scripts/Makefile.lib @@ -121,7 +121,7 @@ endif ifeq ($(CONFIG_KASAN),y) _c_flags += $(if $(patsubst n%,, \ $(KASAN_SANITIZE_$(basetarget).o)$(KASAN_SANITIZE)y), \ - $(CFLAGS_KASAN)) + $(CFLAGS_KASAN), $(CFLAGS_KASAN_NOSANITIZE)) endif ifeq ($(CONFIG_UBSAN),y) _

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[Linux-stable-mirror] Patch "x86/asm: Fix inline asm call constraints for GCC 4.4" has been added to the 4.9-stable tree

by gregkh＠linuxfoundation.org

This is a note to let you know that I've just added the patch titled x86/asm: Fix inline asm call constraints for GCC 4.4 to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum… The filename of the patch is: x86-asm-fix-inline-asm-call-constraints-for-gcc-4.4.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable(a)vger.kernel.org> know about it. >From 520a13c530aeb5f63e011d668c42db1af19ed349 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf <jpoimboe(a)redhat.com> Date: Thu, 28 Sep 2017 16:58:26 -0500 Subject: x86/asm: Fix inline asm call constraints for GCC 4.4 From: Josh Poimboeuf <jpoimboe(a)redhat.com> commit 520a13c530aeb5f63e011d668c42db1af19ed349 upstream. The kernel test bot (run by Xiaolong Ye) reported that the following commit: f5caf621ee35 ("x86/asm: Fix inline asm call constraints for Clang") is causing double faults in a kernel compiled with GCC 4.4. Linus subsequently diagnosed the crash pattern and the buggy commit and found that the issue is with this code: register unsigned int __asm_call_sp asm("esp"); #define ASM_CALL_CONSTRAINT "+r" (__asm_call_sp) Even on a 64-bit kernel, it's using ESP instead of RSP. That causes GCC to produce the following bogus code: ffffffff8147461d: 89 e0 mov %esp,%eax ffffffff8147461f: 4c 89 f7 mov %r14,%rdi ffffffff81474622: 4c 89 fe mov %r15,%rsi ffffffff81474625: ba 20 00 00 00 mov $0x20,%edx ffffffff8147462a: 89 c4 mov %eax,%esp ffffffff8147462c: e8 bf 52 05 00 callq ffffffff814c98f0 <copy_user_generic_unrolled> Despite the absurdity of it backing up and restoring the stack pointer for no reason, the bug is actually the fact that it's only backing up and restoring the lower 32 bits of the stack pointer. The upper 32 bits are getting cleared out, corrupting the stack pointer. So change the '__asm_call_sp' register variable to be associated with the actual full-size stack pointer. This also requires changing the __ASM_SEL() macro to be based on the actual compiled arch size, rather than the CONFIG value, because CONFIG_X86_64 compiles some files with '-m32' (e.g., realmode and vdso). Otherwise Clang fails to build the kernel because it complains about the use of a 64-bit register (RSP) in a 32-bit file. Reported-and-Bisected-and-Tested-by: kernel test robot <xiaolong.ye(a)intel.com> Diagnosed-by: Linus Torvalds <torvalds(a)linux-foundation.org> Signed-off-by: Josh Poimboeuf <jpoimboe(a)redhat.com> Cc: Alexander Potapenko <glider(a)google.com> Cc: Andrey Ryabinin <aryabinin(a)virtuozzo.com> Cc: Andy Lutomirski <luto(a)kernel.org> Cc: Arnd Bergmann <arnd(a)arndb.de> Cc: Dmitriy Vyukov <dvyukov(a)google.com> Cc: LKP <lkp(a)01.org> Cc: Linus Torvalds <torvalds(a)linux-foundation.org> Cc: Matthias Kaehlcke <mka(a)chromium.org> Cc: Miguel Bernal Marin <miguel.bernal.marin(a)linux.intel.com> Cc: Peter Zijlstra <peterz(a)infradead.org> Cc: Thomas Gleixner <tglx(a)linutronix.de> Fixes: f5caf621ee35 ("x86/asm: Fix inline asm call constraints for Clang") Link: http://lkml.kernel.org/r/20170928215826.6sdpmwtkiydiytim@treble Signed-off-by: Ingo Molnar <mingo(a)kernel.org> Cc: Matthias Kaehlcke <mka(a)chromium.org> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- arch/x86/include/asm/asm.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/arch/x86/include/asm/asm.h +++ b/arch/x86/include/asm/asm.h @@ -11,10 +11,12 @@ # define __ASM_FORM_COMMA(x) " " #x "," #endif -#ifdef CONFIG_X86_32 +#ifndef __x86_64__ +/* 32 bit */ # define __ASM_SEL(a,b) __ASM_FORM(a) # define __ASM_SEL_RAW(a,b) __ASM_FORM_RAW(a) #else +/* 64 bit */ # define __ASM_SEL(a,b) __ASM_FORM(b) # define __ASM_SEL_RAW(a,b) __ASM_FORM_RAW(b) #endif Patches currently in stable-queue which might be from jpoimboe(a)redhat.com are queue-4.9/x86-asm-fix-inline-asm-call-constraints-for-gcc-4.4.patch

7 years, 4 months

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[Linux-stable-mirror] Patch "x86/asm: Fix inline asm call constraints for GCC 4.4" has been added to the 4.4-stable tree

by gregkh＠linuxfoundation.org

This is a note to let you know that I've just added the patch titled x86/asm: Fix inline asm call constraints for GCC 4.4 to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum… The filename of the patch is: x86-asm-fix-inline-asm-call-constraints-for-gcc-4.4.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable(a)vger.kernel.org> know about it. >From 520a13c530aeb5f63e011d668c42db1af19ed349 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf <jpoimboe(a)redhat.com> Date: Thu, 28 Sep 2017 16:58:26 -0500 Subject: x86/asm: Fix inline asm call constraints for GCC 4.4 From: Josh Poimboeuf <jpoimboe(a)redhat.com> commit 520a13c530aeb5f63e011d668c42db1af19ed349 upstream. The kernel test bot (run by Xiaolong Ye) reported that the following commit: f5caf621ee35 ("x86/asm: Fix inline asm call constraints for Clang") is causing double faults in a kernel compiled with GCC 4.4. Linus subsequently diagnosed the crash pattern and the buggy commit and found that the issue is with this code: register unsigned int __asm_call_sp asm("esp"); #define ASM_CALL_CONSTRAINT "+r" (__asm_call_sp) Even on a 64-bit kernel, it's using ESP instead of RSP. That causes GCC to produce the following bogus code: ffffffff8147461d: 89 e0 mov %esp,%eax ffffffff8147461f: 4c 89 f7 mov %r14,%rdi ffffffff81474622: 4c 89 fe mov %r15,%rsi ffffffff81474625: ba 20 00 00 00 mov $0x20,%edx ffffffff8147462a: 89 c4 mov %eax,%esp ffffffff8147462c: e8 bf 52 05 00 callq ffffffff814c98f0 <copy_user_generic_unrolled> Despite the absurdity of it backing up and restoring the stack pointer for no reason, the bug is actually the fact that it's only backing up and restoring the lower 32 bits of the stack pointer. The upper 32 bits are getting cleared out, corrupting the stack pointer. So change the '__asm_call_sp' register variable to be associated with the actual full-size stack pointer. This also requires changing the __ASM_SEL() macro to be based on the actual compiled arch size, rather than the CONFIG value, because CONFIG_X86_64 compiles some files with '-m32' (e.g., realmode and vdso). Otherwise Clang fails to build the kernel because it complains about the use of a 64-bit register (RSP) in a 32-bit file. Reported-and-Bisected-and-Tested-by: kernel test robot <xiaolong.ye(a)intel.com> Diagnosed-by: Linus Torvalds <torvalds(a)linux-foundation.org> Signed-off-by: Josh Poimboeuf <jpoimboe(a)redhat.com> Cc: Alexander Potapenko <glider(a)google.com> Cc: Andrey Ryabinin <aryabinin(a)virtuozzo.com> Cc: Andy Lutomirski <luto(a)kernel.org> Cc: Arnd Bergmann <arnd(a)arndb.de> Cc: Dmitriy Vyukov <dvyukov(a)google.com> Cc: LKP <lkp(a)01.org> Cc: Linus Torvalds <torvalds(a)linux-foundation.org> Cc: Matthias Kaehlcke <mka(a)chromium.org> Cc: Miguel Bernal Marin <miguel.bernal.marin(a)linux.intel.com> Cc: Peter Zijlstra <peterz(a)infradead.org> Cc: Thomas Gleixner <tglx(a)linutronix.de> Fixes: f5caf621ee35 ("x86/asm: Fix inline asm call constraints for Clang") Link: http://lkml.kernel.org/r/20170928215826.6sdpmwtkiydiytim@treble Signed-off-by: Ingo Molnar <mingo(a)kernel.org> Cc: Matthias Kaehlcke <mka(a)chromium.org> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- arch/x86/include/asm/asm.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/arch/x86/include/asm/asm.h +++ b/arch/x86/include/asm/asm.h @@ -11,10 +11,12 @@ # define __ASM_FORM_COMMA(x) " " #x "," #endif -#ifdef CONFIG_X86_32 +#ifndef __x86_64__ +/* 32 bit */ # define __ASM_SEL(a,b) __ASM_FORM(a) # define __ASM_SEL_RAW(a,b) __ASM_FORM_RAW(a) #else +/* 64 bit */ # define __ASM_SEL(a,b) __ASM_FORM(b) # define __ASM_SEL_RAW(a,b) __ASM_FORM_RAW(b) #endif Patches currently in stable-queue which might be from jpoimboe(a)redhat.com are queue-4.4/x86-asm-fix-inline-asm-call-constraints-for-gcc-4.4.patch

7 years, 4 months

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