Messages in this thread Patch in this message | | | From | Frederic Weisbecker <> | Subject | [GIT PULL] perf fix | Date | Thu, 8 Apr 2010 19:31:59 +0200 |
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Ingo,
Please pull the perf/urgent branch that can be found at:
git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing.git perf/urgent
Thanks, Frederic ---
Frederic Weisbecker (1): perf: Fix unsafe frame rewinding with hot regs fetching
arch/x86/kernel/dumpstack.h | 8 ++++++-- 1 files changed, 6 insertions(+), 2 deletions(-)
--- commit ab285f2b5290d92b7ec1a6f9aad54308dadf6157 Author: Frederic Weisbecker <fweisbec@gmail.com> Date: Thu Apr 8 14:05:50 2010 +0200
perf: Fix unsafe frame rewinding with hot regs fetching When we fetch the hot regs and rewind to the nth caller, it might happen that we dereference a frame pointer outside the kernel stack boundaries, like in this example: perf_trace_sched_switch+0xd5/0x120 schedule+0x6b5/0x860 retint_careful+0xd/0x21 Since we directly dereference a userspace frame pointer here while rewinding behind retint_careful, this may end up in a crash. Fix this by simply using probe_kernel_address() when we rewind the frame pointer. This issue will have a much more proper fix in the next version of the perf_arch_fetch_caller_regs() API that will only need to rewind to the first caller. Reported-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Tested-by: Eric Dumazet <eric.dumazet@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Paul Mackerras <paulus@samba.org> Cc: David Miller <davem@davemloft.net> Cc: Archs <linux-arch@vger.kernel.org>
diff --git a/arch/x86/kernel/dumpstack.h b/arch/x86/kernel/dumpstack.h index e39e771..e1a93be 100644 --- a/arch/x86/kernel/dumpstack.h +++ b/arch/x86/kernel/dumpstack.h @@ -14,6 +14,8 @@ #define get_bp(bp) asm("movq %%rbp, %0" : "=r" (bp) :) #endif +#include <linux/uaccess.h> + extern void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs, unsigned long *stack, unsigned long bp, char *log_lvl); @@ -42,8 +44,10 @@ static inline unsigned long rewind_frame_pointer(int n) get_bp(frame); #ifdef CONFIG_FRAME_POINTER - while (n--) - frame = frame->next_frame; + while (n--) { + if (probe_kernel_address(&frame->next_frame, frame)) + break; + } #endif return (unsigned long)frame;
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