[compiler-rt] [dfsan] Fix release_shadow_space.c (PR #94770)
via llvm-commits
llvm-commits at lists.llvm.org
Fri Jun 7 09:57:17 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-compiler-rt-sanitizer
Author: Thurston Dang (thurstond)
<details>
<summary>Changes</summary>
DFSan's sscanf is incorrect (https://github.com/llvm/llvm-project/issues/94769), which results in erroneous matches when scraping RSS /proc/maps. This patch works around the issue by using strstr as a secondary check.
It also adds a loose validity check for the initial RSS, to guard against future regressions in get_rss_kb().
Fixes https://github.com/llvm/llvm-project/issues/91287
---
Full diff: https://github.com/llvm/llvm-project/pull/94770.diff
1 Files Affected:
- (modified) compiler-rt/test/dfsan/release_shadow_space.c (+10-4)
``````````diff
diff --git a/compiler-rt/test/dfsan/release_shadow_space.c b/compiler-rt/test/dfsan/release_shadow_space.c
index 60dec98ebec49..0f0e1a9c731cb 100644
--- a/compiler-rt/test/dfsan/release_shadow_space.c
+++ b/compiler-rt/test/dfsan/release_shadow_space.c
@@ -3,9 +3,6 @@
// DFSAN_OPTIONS=no_huge_pages_for_shadow=false RUN: %clang_dfsan %s -DORIGIN_TRACKING -mllvm -dfsan-track-origins=1 -o %t && %run %t
// DFSAN_OPTIONS=no_huge_pages_for_shadow=true RUN: %clang_dfsan %s -DORIGIN_TRACKING -mllvm -dfsan-track-origins=1 -o %t && %run %t
-// This test is flaky right now: https://github.com/llvm/llvm-project/issues/91287
-// UNSUPPORTED: target={{.*}}
-
#include <assert.h>
#include <sanitizer/dfsan_interface.h>
#include <stdbool.h>
@@ -26,7 +23,11 @@ size_t get_rss_kb() {
char buf[256];
while (fgets(buf, sizeof(buf), f) != NULL) {
int64_t rss;
- if (sscanf(buf, "Rss: %ld kB", &rss) == 1)
+ // DFSan's sscanf is broken and doesn't check for ordinary characters in
+ // the format string, hence we use strstr as a secondary check
+ // (https://github.com/llvm/llvm-project/issues/94769).
+ if ((sscanf(buf, "Rss: %ld kB", &rss) == 1) &&
+ (strstr(buf, "Rss: ") != NULL))
ret += rss;
}
assert(feof(f));
@@ -73,6 +74,11 @@ int main(int argc, char **argv) {
before, after_mmap, after_mmap_and_set_label, after_fixed_mmap,
after_mmap_and_set_label2, after_munmap);
+ // This is orders of magnitude larger than we expect (typically < 10,000KB).
+ // It is a quick check to ensure that the RSS calculation function isn't
+ // egregriously wrong.
+ assert(before < 1000000);
+
const size_t mmap_cost_kb = map_size >> 10;
// Shadow space (1:1 with application memory)
const size_t mmap_shadow_cost_kb = sizeof(dfsan_label) * mmap_cost_kb;
``````````
</details>
https://github.com/llvm/llvm-project/pull/94770
More information about the llvm-commits
mailing list