From: Josh Law <hlcj1234567@gmail.com>
To: "Liam R . Howlett" <Liam.Howlett@oracle.com>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Alice Ryhl <aliceryhl@google.com>,
Andrew Ballance <andrewjballance@gmail.com>,
linux-kernel@vger.kernel.org, maple-tree@lists.infradead.org,
linux-mm@kvack.org, Josh Law <objecting@objecting.org>
Subject: [PATCH v2] lib/maple_tree: fix potential NULL dereference in mas_pop_node()
Date: Fri, 13 Mar 2026 07:31:32 +0000 [thread overview]
Message-ID: <20260313073132.159184-1-objecting@objecting.org> (raw)
If kmem_cache_alloc_from_sheaf() returns NULL (possible under
GFP_NOWAIT pressure), mas_pop_node() falls through to the out label
and dereferences the NULL pointer in memset(ret, 0, sizeof(*ret)).
Add a NULL check after the sheaf allocation to bail out early.
Signed-off-by: Josh Law <objecting@objecting.org>
---
v2: drop WARN_ON_ONCE — this is a recoverable allocation failure,
not a state that warrants a warning splat.
lib/maple_tree.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 739918e859e5..1eaaa5f964e9 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -1063,6 +1063,8 @@ static __always_inline struct maple_node *mas_pop_node(struct ma_state *mas)
return NULL;
ret = kmem_cache_alloc_from_sheaf(maple_node_cache, GFP_NOWAIT, mas->sheaf);
+ if (!ret)
+ return NULL;
out:
memset(ret, 0, sizeof(*ret));
--
2.34.1
reply other threads:[~2026-03-13 7:31 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260313073132.159184-1-objecting@objecting.org \
--to=hlcj1234567@gmail.com \
--cc=Liam.Howlett@oracle.com \
--cc=akpm@linux-foundation.org \
--cc=aliceryhl@google.com \
--cc=andrewjballance@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=maple-tree@lists.infradead.org \
--cc=objecting@objecting.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox