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sysfs: upgrade OOB write by buggy .show hook into WARNing

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Buggy .show hook will get just 1 line of dmesg:

	fill_read_buffer: ext4_attr_show+0x0/0x600 returned bad count

It may or may not oops later in some unrelated process.

But buggy .show hook most likely is corrupting random memory past sysfs
buffer therefore deserving more. WARN, make it more visible and let
QA machines panic earlier.

Also, delete useless cast -- "count" is >=0 at this point.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Link: https://patch.msgid.link/3cc3e8c6-c6e8-4625-a88f-f5708b935dab@p183
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alexey Dobriyan
2026-05-07 12:01:43 +03:00
committed by Greg Kroah-Hartman
parent 896df22ee5
commit f71cc65c01
1 changed files with 2 additions and 3 deletions
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5
fs/sysfs/file.c
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@@ -70,9 +70,8 @@ static int sysfs_kf_seq_show(struct seq_file *sf, void *v)
* The code works fine with PAGE_SIZE return but it's likely to
* indicate truncated result or overflow in normal use cases.
*/
if (count >= (ssize_t)PAGE_SIZE) {
printk("fill_read_buffer: %pS returned bad count\n",
ops->show);
if (count >= PAGE_SIZE) {
WARN(1, "OOB write or bad count %zd at %pS\n", count, ops->show);
/* Try to struggle along */
count = PAGE_SIZE - 1;
}