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authorRoland McGrath <roland@redhat.com>2010-07-21 17:44:12 -0700
committerRoland McGrath <roland@redhat.com>2010-07-21 17:44:12 -0700
commit0327559151c6886814d6d5b373b4bf6de63fb9f6 (patch)
parentcd5b8f8755a89a57fc8c408d284b8b613f090345 (diff)
x86: auditsyscall: fix fastpath return value after reschedule
In the CONFIG_AUDITSYSCALL fast-path for x86 64-bit system calls, we can pass a bad return value and/or error indication for the system call to audit_syscall_exit(). This happens when TIF_NEED_RESCHED was set as the system call returned, so we went out to schedule() and came back to the exit-audit fast-path. The fix is to reload the user return value register from the pt_regs before using it for audit_syscall_exit(). Both the 32-bit kernel's fast path and the 64-bit kernel's 32-bit system call fast paths work slightly differently, so that they always leave the fast path entirely to reschedule and don't return there, so they don't have the analogous bugs. Reported-by: Alexander Viro <aviro@redhat.com> Signed-off-by: Roland McGrath <roland@redhat.com>
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 0697ff13983..4db7c4d12ff 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -571,8 +571,8 @@ auditsys:
* masked off.
- movq %rax,%rsi /* second arg, syscall return value */
- cmpq $0,%rax /* is it < 0? */
+ movq RAX-ARGOFFSET(%rsp),%rsi /* second arg, syscall return value */
+ cmpq $0,%rsi /* is it < 0? */
setl %al /* 1 if so, 0 if not */
movzbl %al,%edi /* zero-extend that into %edi */
inc %edi /* first arg, 0->1(AUDITSC_SUCCESS), 1->2(AUDITSC_FAILURE) */