The patch titled
Subject: watchdog/perf: optimize bytes copied and remove manual NUL-termination
has been added to the -mm mm-nonmm-unstable branch. Its filename is
watchdog-perf-optimize-bytes-copied-and-remove-manual-nul-termination.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/watchdog-perf-optimize-bytes-copied-and-remove-manual-nul-termination.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Thorsten Blum <thorsten.blum@xxxxxxxxx>
Subject: watchdog/perf: optimize bytes copied and remove manual NUL-termination
Date: Thu, 13 Mar 2025 14:30:02 +0100
Currently, up to 23 bytes of the source string are copied to the
destination buffer (including the comma and anything after it), only to
then manually NUL-terminate the destination buffer again at index 'len'
(where the comma was found).
Fix this by calling strscpy() with 'len' instead of the destination buffer
size to copy only as many bytes from the source string as needed.
Change the length check to allow 'len' to be less than or equal to the
destination buffer size to fill the whole buffer if needed.
Remove the if-check for the return value of strscpy(), because calling
strscpy() with 'len' always truncates the source string at the comma as
expected and NUL-terminates the destination buffer at the corresponding
index instead. Remove the manual NUL-termination.
No functional changes intended.
Link: https://lkml.kernel.org/r/20250313133004.36406-2-thorsten.blum@xxxxxxxxx
Signed-off-by: Thorsten Blum <thorsten.blum@xxxxxxxxx>
Cc: Song Liu <song@xxxxxxxxxx>
Cc: Thomas Gleinxer <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/watchdog_perf.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
--- a/kernel/watchdog_perf.c~watchdog-perf-optimize-bytes-copied-and-remove-manual-nul-termination
+++ a/kernel/watchdog_perf.c
@@ -294,12 +294,10 @@ void __init hardlockup_config_perf_event
} else {
unsigned int len = comma - str;
- if (len >= sizeof(buf))
+ if (len > sizeof(buf))
return;
- if (strscpy(buf, str, sizeof(buf)) < 0)
- return;
- buf[len] = 0;
+ strscpy(buf, str, len);
if (kstrtoull(buf, 16, &config))
return;
}
_
Patches currently in -mm which might be from thorsten.blum@xxxxxxxxx are
arm-pgtable-remove-duplicate-included-header-file.patch
watchdog-perf-optimize-bytes-copied-and-remove-manual-nul-termination.patch
