The patch titled
Subject: mm/damon/dbgfs: fix bogus string length
has been added to the -mm mm-unstable branch. Its filename is
mm-damon-dbgfs-implement-deprecation-notice-file-fix.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-damon-dbgfs-implement-deprecation-notice-file-fix.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Arnd Bergmann <arnd@xxxxxxxx>
Subject: mm/damon/dbgfs: fix bogus string length
Date: Fri, 2 Feb 2024 13:43:26 +0100
gcc correctly points out that using strnlen() on a fixed size array
is nonsense with an overlong limit:
mm/damon/dbgfs.c: In function 'damon_dbgfs_deprecated_read':
mm/damon/dbgfs.c:814:19: error: 'strnlen' specified bound 1024 exceeds source size 512 [-Werror=stringop-overread]
814 | int len = strnlen(kbuf, 1024);
| ^~~~~~~~~~~~~~~~~~~
mm/damon/dbgfs.c:813:14: note: source object allocated here
813 | char kbuf[512] = DAMON_DBGFS_DEPRECATION_NOTICE;
| ^~~~
In fact, neither of the arbitrary limits are needed here: The first
one can just be a static const string and avoid wasting any more
space then necessary, and the strnlen() can be either strlen() or
sizeof(kbuf)-1, both of which the compiler turns into the same
constant here.
Link: https://lkml.kernel.org/r/20240202124339.892862-1-arnd@xxxxxxxxxx
Fixes: adf9047adfff ("mm/damon/dbgfs: implement deprecation notice file")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Alex Shi <alexs@xxxxxxxxxx>
Cc: Hu Haowen <2023002089@xxxxxxxxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: SeongJae Park <sj@xxxxxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Cc: Yanteng Si <siyanteng@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/damon/dbgfs.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
--- a/mm/damon/dbgfs.c~mm-damon-dbgfs-implement-deprecation-notice-file-fix
+++ a/mm/damon/dbgfs.c
@@ -808,13 +808,12 @@ static void dbgfs_destroy_ctx(struct dam
static ssize_t damon_dbgfs_deprecated_read(struct file *file,
char __user *buf, size_t count, loff_t *ppos)
{
- char kbuf[512] = "DAMON debugfs interface is deprecated, "
+ static const char kbuf[512] = "DAMON debugfs interface is deprecated, "
"so users should move to DAMON_SYSFS. If you cannot, "
"please report your usecase to damon@xxxxxxxxxxxxxxx and "
"linux-mm@xxxxxxxxx.\n";
- int len = strnlen(kbuf, 1024);
- return simple_read_from_buffer(buf, count, ppos, kbuf, len);
+ return simple_read_from_buffer(buf, count, ppos, kbuf, strlen(kbuf));
}
/*
_
Patches currently in -mm which might be from arnd@xxxxxxxx are
mm-damon-dbgfs-implement-deprecation-notice-file-fix.patch
