github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-07-27 17:47:41 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

perf tools: Fix get_max_num() size_t underflow on empty sysfs file

Browse Source 
get_max_num() reads a sysfs file (cpu/possible, cpu/present, or
node/possible) and scans backward from the end to find the last
number.  If the file is empty, filename__read_str() returns num == 0.
The loop `while (--num)` decrements the size_t from 0 to SIZE_MAX,
reading backward across the heap until a comma or hyphen is found
or unmapped memory is hit.

Add an early return for empty files before the backward scan.

Fixes: 7780c25bae ("perf tools: Allow ability to map cpus to nodes easily")
Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Reviewed-by: Ian Rogers <irogers@google.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Ian Rogers <irogers@google.com>
Assisted-by: Claude:claude-opus-4.6
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Arnaldo Carvalho de Melo 2026-06-06 20:37:52 -03:00
parent f54ce06049
commit 0a012113bb
1 changed files with 6 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
tools/perf/util/cpumap.c
View File

@ -448,6 +448,12 @@ static int get_max_num(char *path, int *max)
buf[num] = '\0';
/* empty file — nothing to parse */
if (num == 0) {
err = -1;
goto out;
}
/* start on the right, to find highest node num */
while (--num) {
if ((buf[num] == ',') || (buf[num] == '-')) {