* [PATCH] dlm: check negative length in dlm_search_rsb_tree
@ 2026-05-15 7:39 Joseph Qi
2026-05-15 13:30 ` Alexander Aring
0 siblings, 1 reply; 3+ messages in thread
From: Joseph Qi @ 2026-05-15 7:39 UTC (permalink / raw)
To: Alexander Aring, David Teigland; +Cc: gfs2, linux-kernel
commit 080e5563f878 only checks for len > DLM_RESNAME_MAXLEN, which does
not catch negative values. While the input 'len' can be negative and a
negative int passed to memcpy() is implicitly converted to a large
size_t, causing a stack buffer overflow on the key[] array.
Fix this by also rejecting len <= 0.
Signed-off-by: Joseph Qi <joseph.qi@linux.alibaba.com>
---
fs/dlm/lock.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index c381e1028446..124f68c8e653 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -626,8 +626,10 @@ int dlm_search_rsb_tree(struct rhashtable *rhash, const void *name, int len,
struct dlm_rsb **r_ret)
{
char key[DLM_RESNAME_MAXLEN] = {};
- if (len > DLM_RESNAME_MAXLEN)
+
+ if (len <= 0 || len > DLM_RESNAME_MAXLEN)
return -EINVAL;
+
memcpy(key, name, len);
*r_ret = rhashtable_lookup_fast(rhash, &key, dlm_rhash_rsb_params);
if (*r_ret)
--
2.39.3
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] dlm: check negative length in dlm_search_rsb_tree
2026-05-15 7:39 [PATCH] dlm: check negative length in dlm_search_rsb_tree Joseph Qi
@ 2026-05-15 13:30 ` Alexander Aring
2026-05-17 1:30 ` Joseph Qi
0 siblings, 1 reply; 3+ messages in thread
From: Alexander Aring @ 2026-05-15 13:30 UTC (permalink / raw)
To: Joseph Qi; +Cc: David Teigland, gfs2, linux-kernel
Hi,
On Fri, May 15, 2026 at 3:39 AM Joseph Qi <joseph.qi@linux.alibaba.com> wrote:
>
> commit 080e5563f878 only checks for len > DLM_RESNAME_MAXLEN, which does
> not catch negative values. While the input 'len' can be negative and a
> negative int passed to memcpy() is implicitly converted to a large
> size_t, causing a stack buffer overflow on the key[] array.
>
> Fix this by also rejecting len <= 0.
or change the parameter to unsigned?
- Alex
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] dlm: check negative length in dlm_search_rsb_tree
2026-05-15 13:30 ` Alexander Aring
@ 2026-05-17 1:30 ` Joseph Qi
0 siblings, 0 replies; 3+ messages in thread
From: Joseph Qi @ 2026-05-17 1:30 UTC (permalink / raw)
To: Alexander Aring; +Cc: David Teigland, gfs2, linux-kernel
On 5/15/26 9:30 PM, Alexander Aring wrote:
> Hi,
>
> On Fri, May 15, 2026 at 3:39 AM Joseph Qi <joseph.qi@linux.alibaba.com> wrote:
>>
>> commit 080e5563f878 only checks for len > DLM_RESNAME_MAXLEN, which does
>> not catch negative values. While the input 'len' can be negative and a
>> negative int passed to memcpy() is implicitly converted to a large
>> size_t, causing a stack buffer overflow on the key[] array.
>>
>> Fix this by also rejecting len <= 0.
>
> or change the parameter to unsigned?
>
Yes, it would be fine. I'll work on it and send v2 later.
Thanks,
Joseph
^ permalink raw reply [flat|nested] 3+ messages in thread
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2026-05-15 7:39 [PATCH] dlm: check negative length in dlm_search_rsb_tree Joseph Qi
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