From: Will Deacon <[email protected]>

3.4.106-rc1 review patch.  If anyone has any objections, please let me know.

------------------


commit 60916a9382e88fbf5e54fd36a3e658efd7ab7bed upstream.

syscall_get_nr can return -1 in the case that the task is not executing
a system call.

This patch fixes perf_syscall_{enter,exit} to check that the syscall
number is valid before using it as an index into a bitmap.

Link: 
http://lkml.kernel.org/r/[email protected]

Cc: Jason Baron <[email protected]>
Cc: Wade Farnsworth <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Signed-off-by: Will Deacon <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>
Signed-off-by: Zefan Li <[email protected]>
---
 kernel/trace/trace_syscalls.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index c9ce09a..aed38fd 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -519,6 +519,8 @@ static void perf_syscall_enter(void *ignore, struct pt_regs 
*regs, long id)
        int size;
 
        syscall_nr = syscall_get_nr(current, regs);
+       if (syscall_nr < 0)
+               return;
        if (!test_bit(syscall_nr, enabled_perf_enter_syscalls))
                return;
 
@@ -593,6 +595,8 @@ static void perf_syscall_exit(void *ignore, struct pt_regs 
*regs, long ret)
        int size;
 
        syscall_nr = syscall_get_nr(current, regs);
+       if (syscall_nr < 0)
+               return;
        if (!test_bit(syscall_nr, enabled_perf_exit_syscalls))
                return;
 
-- 
1.9.1

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