gh-144194: Fix mmap failure check in perf_jit_trampoline.c

stratakis · stratakis · commit 55402f64d849 · 2026-01-28T14:02:19.000+01:00
mmap() returns MAP_FAILED ((void*)-1) on error, not NULL. The current
check never detects mmap failures, so jitdump initialization proceeds
even when the memory mapping fails.
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-01-23-20-20-42.gh-issue-144194.IbXfxd.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-01-23-20-20-42.gh-issue-144194.IbXfxd.rst
@@ -0,0 +1 @@
+Fix error handling in perf jitdump initialization on memory allocation failure.
diff --git a/Python/perf_jit_trampoline.c b/Python/perf_jit_trampoline.c
@@ -1083,7 +1083,8 @@ static void* perf_map_jit_init(void) {
         0                        // Offset 0 (first page)
     );
 
-    if (perf_jit_map_state.mapped_buffer == NULL) {
+    if (perf_jit_map_state.mapped_buffer == MAP_FAILED) {
+        perf_jit_map_state.mapped_buffer = NULL;
         close(fd);
         return NULL;  // Memory mapping failed
     }

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	`+Fix error handling in perf jitdump initialization on memory allocation failure.`
Original file line number	Diff line number	Diff line change
`@@ -1083,7 +1083,8 @@ static void* perf_map_jit_init(void) {`
`1083`	`1083`	`0 // Offset 0 (first page)`
`1084`	`1084`	`);`
`1085`	`1085`
`1086`		`- if (perf_jit_map_state.mapped_buffer == NULL) {`
	`1086`	`+ if (perf_jit_map_state.mapped_buffer == MAP_FAILED) {`
	`1087`	`+ perf_jit_map_state.mapped_buffer = NULL;`
`1087`	`1088`	`close(fd);`
`1088`	`1089`	`return NULL; // Memory mapping failed`
`1089`	`1090`	`}`