The quilt patch titled Subject: x86/kexec: fix potential cmem->ranges out of bounds has been removed from the -mm tree. Its filename was x86-kexec-fix-potential-cmem-ranges-out-of-bounds.patch

This patch was dropped because an updated version will be issued

------------------------------------------------------ From: fuqiang wang fuqiang.wang@easystack.cn Subject: x86/kexec: fix potential cmem->ranges out of bounds Date: Mon, 8 Jan 2024 21:06:47 +0800

In memmap_exclude_ranges(), elfheader will be excluded from crashk_res. In the current x86 architecture code, the elfheader is always allocated at crashk_res.start. It seems that there won't be a new split range. But it depends on the allocation position of elfheader in crashk_res. To avoid potential out of bounds in future, add a extra slot.

The similar issue also exists in fill_up_crash_elf_data(). The range to be excluded is [0, 1M], start (0) is special and will not appear in the middle of existing cmem->ranges[]. But in cast the low 1M could be changed in the future, add a extra slot too.

Without this patch, kdump kernel will fail to be loaded by kexec_file_load,

[ 139.736948] UBSAN: array-index-out-of-bounds in arch/x86/kernel/crash.c:350:25 [ 139.742360] index 0 is out of range for type 'range [*]' [ 139.745695] CPU: 0 UID: 0 PID: 5778 Comm: kexec Not tainted 6.15.0-0.rc3.20250425git02ddfb981de8.32.fc43.x86_64 #1 PREEMPT(lazy) [ 139.745698] Hardware name: Amazon EC2 c5.large/, BIOS 1.0 10/16/2017 [ 139.745699] Call Trace: [ 139.745700] <TASK> [ 139.745701] dump_stack_lvl+0x5d/0x80 [ 139.745706] ubsan_epilogue+0x5/0x2b [ 139.745709] __ubsan_handle_out_of_bounds.cold+0x54/0x59 [ 139.745711] crash_setup_memmap_entries+0x2d9/0x330 [ 139.745716] setup_boot_parameters+0xf8/0x6a0 [ 139.745720] bzImage64_load+0x41b/0x4e0 [ 139.745722] ? find_next_iomem_res+0x109/0x140 [ 139.745727] ? locate_mem_hole_callback+0x109/0x170 [ 139.745737] kimage_file_alloc_init+0x1ef/0x3e0 [ 139.745740] __do_sys_kexec_file_load+0x180/0x2f0 [ 139.745742] do_syscall_64+0x7b/0x160 [ 139.745745] ? do_user_addr_fault+0x21a/0x690 [ 139.745747] ? exc_page_fault+0x7e/0x1a0 [ 139.745749] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 139.745751] RIP: 0033:0x7f7712c84e4d

Previously discussed link: [1] https://lore.kernel.org/kexec/ZXk2oBf%2FT1Ul6o0c@MiWiFi-R3L-srv/ [2] https://lore.kernel.org/kexec/273284e8-7680-4f5f-8065-c5d780987e59@easystack... [3] https://lore.kernel.org/kexec/ZYQ6O%2F57sHAPxTHm@MiWiFi-R3L-srv/

Link: https://lkml.kernel.org/r/20240108130720.228478-1-fuqiang.wang@easystack.cn Signed-off-by: fuqiang wang fuqiang.wang@easystack.cn Acked-by: Baoquan He bhe@redhat.com Reported-by: Coiby Xu coxu@redhat.com Closes: https://lkml.kernel.org/r/4de3c2onosr7negqnfhekm4cpbklzmsimgdfv33c52dktqpza5... Cc: Vivek Goyal vgoyal@redhat.com Cc: Dave Young dyoung@redhat.com Cc: x86@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

arch/x86/kernel/crash.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-)

--- a/arch/x86/kernel/crash.c~x86-kexec-fix-potential-cmem-ranges-out-of-bounds +++ a/arch/x86/kernel/crash.c @@ -165,8 +165,18 @@ static struct crash_mem *fill_up_crash_e /* * Exclusion of crash region and/or crashk_low_res may cause * another range split. So add extra two slots here. + * + * Exclusion of low 1M may not cause another range split, because the + * range of exclude is [0, 1M] and the condition for splitting a new + * region is that the start, end parameters are both in a certain + * existing region in cmem and cannot be equal to existing region's + * start or end. Obviously, the start of [0, 1M] cannot meet this + * condition. + * + * But in order to lest the low 1M could be changed in the future, + * (e.g. [stare, 1M]), add a extra slot. */ - nr_ranges += 2; + nr_ranges += 3; cmem = vzalloc(struct_size(cmem, ranges, nr_ranges)); if (!cmem) return NULL; @@ -298,9 +308,16 @@ int crash_setup_memmap_entries(struct ki struct crash_memmap_data cmd; struct crash_mem *cmem;

- cmem = vzalloc(struct_size(cmem, ranges, 1)); + /* + * In the current x86 architecture code, the elfheader is always + * allocated at crashk_res.start. But it depends on the allocation + * position of elfheader in crashk_res. To avoid potential out of + * bounds in future, add a extra slot. + */ + cmem = vzalloc(struct_size(cmem, ranges, 2)); if (!cmem) return -ENOMEM; + cmem->max_nr_ranges = 2;

memset(&cmd, 0, sizeof(struct crash_memmap_data)); cmd.params = params; _

Patches currently in -mm which might be from fuqiang.wang@easystack.cn are