[compiler-rt] e1041ed - [sanitizer] move a pointer dereference after its null check

[Vitaly Buka via llvm-commits]

Author: Wu, Yingcong
Date: 2023-04-26T18:59:17-07:00
New Revision: e1041ed5761c03bde830a2932c719901d43a8d7e

URL: https://github.com/llvm/llvm-project/commit/e1041ed5761c03bde830a2932c719901d43a8d7e
DIFF: https://github.com/llvm/llvm-project/commit/e1041ed5761c03bde830a2932c719901d43a8d7e.diff

LOG: [sanitizer] move a pointer dereference after its null check

The dereference of pointer `ctx` is not protected by its null check, this could be problematic.

Reviewed By: vitalybuka, MaskRay

Differential Revision: https://reviews.llvm.org/D149011

Added: 
    

Modified: 
    compiler-rt/lib/sanitizer_common/sanitizer_common_syscalls.inc

Removed: 
    


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diff  --git a/compiler-rt/lib/sanitizer_common/sanitizer_common_syscalls.inc b/compiler-rt/lib/sanitizer_common/sanitizer_common_syscalls.inc
index 93b988ba1639..3900bcf22b7a 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_common_syscalls.inc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_common_syscalls.inc
@@ -1374,9 +1374,8 @@ PRE_SYSCALL(io_setup)(long nr_reqs, void **ctx) {
 }
 
 POST_SYSCALL(io_setup)(long res, long nr_reqs, void **ctx) {
-  if (res >= 0) {
-    if (ctx)
-      POST_WRITE(ctx, sizeof(*ctx));
+  if (res >= 0 && ctx) {
+    POST_WRITE(ctx, sizeof(*ctx));
     // (*ctx) is actually a pointer to a kernel mapped page, and there are
     // people out there who are crazy enough to peek into that page's 32-byte
     // header.