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authorFrederic Weisbecker <fweisbec@gmail.com>2010-04-08 14:05:50 +0200
committerFrederic Weisbecker <fweisbec@gmail.com>2010-04-08 19:03:28 +0200
commitab285f2b5290d92b7ec1a6f9aad54308dadf6157 (patch)
tree70ffdac1d267401330b487bc6f502a9206a4ae6b /arch/x86
parent134fbadf028a5977a1b06b0253d3ee33e6f0c642 (diff)
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>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kernel/dumpstack.h8
1 files changed, 6 insertions, 2 deletions
diff --git a/arch/x86/kernel/dumpstack.h b/arch/x86/kernel/dumpstack.h
index e39e77168a3..e1a93be4fd4 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;