6.9-stable review patch. If anyone has any objections, please let me know.
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From: Heiko Carstens hca@linux.ibm.com
[ Upstream commit 62b672c4ba90e726cc39b5c3d6dffd1ca817e143 ]
Clear the backchain of the extra stack frame added by the vdso user wrapper code. This allows the user stack walker to detect and skip the non-standard stack frame. Without this an incorrect instruction pointer would be added to stack traces, and stack frame walking would be continued with a more or less random back chain.
Fixes: aa44433ac4ee ("s390: add USER_STACKTRACE support") Reviewed-by: Jens Remus jremus@linux.ibm.com Signed-off-by: Heiko Carstens hca@linux.ibm.com Signed-off-by: Alexander Gordeev agordeev@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/s390/include/asm/processor.h | 1 + arch/s390/kernel/asm-offsets.c | 1 + arch/s390/kernel/stacktrace.c | 28 ++++++++++++++++++--- arch/s390/kernel/vdso.c | 13 +++++++--- arch/s390/kernel/vdso64/vdso_user_wrapper.S | 1 + 5 files changed, 36 insertions(+), 8 deletions(-)
diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h index db9982f0e8cd0..bbbdc5abe2b2c 100644 --- a/arch/s390/include/asm/processor.h +++ b/arch/s390/include/asm/processor.h @@ -98,6 +98,7 @@ void cpu_detect_mhz_feature(void);
extern const struct seq_operations cpuinfo_op; extern void execve_tail(void); +unsigned long vdso_text_size(void); unsigned long vdso_size(void);
/* diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c index 28017c418442b..2f65bca2f3f1c 100644 --- a/arch/s390/kernel/asm-offsets.c +++ b/arch/s390/kernel/asm-offsets.c @@ -66,6 +66,7 @@ int main(void) OFFSET(__SF_SIE_CONTROL_PHYS, stack_frame, sie_control_block_phys); DEFINE(STACK_FRAME_OVERHEAD, sizeof(struct stack_frame)); BLANK(); + OFFSET(__SFUSER_BACKCHAIN, stack_frame_user, back_chain); DEFINE(STACK_FRAME_USER_OVERHEAD, sizeof(struct stack_frame_user)); OFFSET(__SFVDSO_RETURN_ADDRESS, stack_frame_vdso_wrapper, return_address); DEFINE(STACK_FRAME_VDSO_OVERHEAD, sizeof(struct stack_frame_vdso_wrapper)); diff --git a/arch/s390/kernel/stacktrace.c b/arch/s390/kernel/stacktrace.c index b4485b0c7f06b..640363b2a1059 100644 --- a/arch/s390/kernel/stacktrace.c +++ b/arch/s390/kernel/stacktrace.c @@ -92,10 +92,16 @@ static inline bool ip_invalid(unsigned long ip) return false; }
+static inline bool ip_within_vdso(unsigned long ip) +{ + return in_range(ip, current->mm->context.vdso_base, vdso_text_size()); +} + void arch_stack_walk_user_common(stack_trace_consume_fn consume_entry, void *cookie, struct perf_callchain_entry_ctx *entry, const struct pt_regs *regs, bool perf) { + struct stack_frame_vdso_wrapper __user *sf_vdso; struct stack_frame_user __user *sf; unsigned long ip, sp; bool first = true; @@ -112,11 +118,25 @@ void arch_stack_walk_user_common(stack_trace_consume_fn consume_entry, void *coo while (1) { if (__get_user(sp, &sf->back_chain)) break; + /* + * VDSO entry code has a non-standard stack frame layout. + * See VDSO user wrapper code for details. + */ + if (!sp && ip_within_vdso(ip)) { + sf_vdso = (void __user *)sf; + if (__get_user(ip, &sf_vdso->return_address)) + break; + sp = (unsigned long)sf + STACK_FRAME_VDSO_OVERHEAD; + sf = (void __user *)sp; + if (__get_user(sp, &sf->back_chain)) + break; + } else { + sf = (void __user *)sp; + if (__get_user(ip, &sf->gprs[8])) + break; + } /* Sanity check: ABI requires SP to be 8 byte aligned. */ - if (!sp || sp & 0x7) - break; - sf = (void __user *)sp; - if (__get_user(ip, &sf->gprs[8])) + if (sp & 0x7) break; if (ip_invalid(ip)) { /* diff --git a/arch/s390/kernel/vdso.c b/arch/s390/kernel/vdso.c index a45b3a4c91db0..2f967ac2b8e3e 100644 --- a/arch/s390/kernel/vdso.c +++ b/arch/s390/kernel/vdso.c @@ -210,17 +210,22 @@ static unsigned long vdso_addr(unsigned long start, unsigned long len) return addr; }
-unsigned long vdso_size(void) +unsigned long vdso_text_size(void) { - unsigned long size = VVAR_NR_PAGES * PAGE_SIZE; + unsigned long size;
if (is_compat_task()) - size += vdso32_end - vdso32_start; + size = vdso32_end - vdso32_start; else - size += vdso64_end - vdso64_start; + size = vdso64_end - vdso64_start; return PAGE_ALIGN(size); }
+unsigned long vdso_size(void) +{ + return vdso_text_size() + VVAR_NR_PAGES * PAGE_SIZE; +} + int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) { unsigned long addr = VDSO_BASE; diff --git a/arch/s390/kernel/vdso64/vdso_user_wrapper.S b/arch/s390/kernel/vdso64/vdso_user_wrapper.S index deee8ca9cdbf0..e26e68675c08d 100644 --- a/arch/s390/kernel/vdso64/vdso_user_wrapper.S +++ b/arch/s390/kernel/vdso64/vdso_user_wrapper.S @@ -23,6 +23,7 @@ __kernel_\func: CFI_VAL_OFFSET 15,-STACK_FRAME_USER_OVERHEAD stg %r14,__SFVDSO_RETURN_ADDRESS(%r15) CFI_REL_OFFSET 14,__SFVDSO_RETURN_ADDRESS + xc __SFUSER_BACKCHAIN(8,%r15),__SFUSER_BACKCHAIN(%r15) brasl %r14,__s390_vdso_\func lg %r14,__SFVDSO_RETURN_ADDRESS(%r15) CFI_RESTORE 14