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[Precise,CVE-2014-7826,1/2] tracing/syscalls: Fix perf syscall tracing when syscall_nr == -1

Message ID 1415876067-14704-2-git-send-email-luis.henriques@canonical.com
State New
Headers show

Commit Message

Luis Henriques Nov. 13, 2014, 10:54 a.m. UTC
From: Will Deacon <will.deacon@arm.com>

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/1345137254-7377-1-git-send-email-will.deacon@arm.com

Cc: Jason Baron <jbaron@redhat.com>
Cc: Wade Farnsworth <wade_farnsworth@mentor.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
(cherry picked from commit 60916a9382e88fbf5e54fd36a3e658efd7ab7bed)
[ luis: prereq for
  086ba77a6db0 "tracing/syscalls: Ignore numbers outside NR_syscalls' range" ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
 kernel/trace/trace_syscalls.c | 4 ++++
 1 file changed, 4 insertions(+)
diff mbox

Patch

diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 7c75bbb9d541..22a7c9bb31d4 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;