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Message-Id: <20241104035105.192960-1-danielyangkang@gmail.com>
Date: Sun, 3 Nov 2024 19:51:05 -0800
From: Daniel Yang <danielyangkang@...il.com>
To: Jens Axboe <axboe@...nel.dk>,
Pavel Begunkov <asml.silence@...il.com>,
io-uring@...r.kernel.org (open list:IO_URING),
linux-kernel@...r.kernel.org (open list)
Cc: Daniel Yang <danielyangkang@...il.com>,
syzbot+05c0f12a4d43d656817e@...kaller.appspotmail.com
Subject: [PATCH] io_uring/rsrc: fix null ptr dereference in io_sqe_buffer_register
The call stack io_sqe_buffer_register -> io_buffer_account_pin ->
headpage_already_acct results in a null ptr dereference in the for loop.
There is no guarantee that ctx->buf_table.nodes[i] is an allocated node
so add a check if null before dereferencing.
Signed-off-by: Daniel Yang <danielyangkang@...il.com>
Reported-by: syzbot+05c0f12a4d43d656817e@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=05c0f12a4d43d656817e
Fixes: 661768085e99 ("io_uring/rsrc: get rid of the empty node and dummy_ubuf")
---
io_uring/rsrc.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index af60d9f59..e2edb752a 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -581,6 +581,8 @@ static bool headpage_already_acct(struct io_ring_ctx *ctx, struct page **pages,
/* check previously registered pages */
for (i = 0; i < ctx->buf_table.nr; i++) {
struct io_rsrc_node *node = ctx->buf_table.nodes[i];
+ if (!node)
+ continue;
struct io_mapped_ubuf *imu = node->buf;
for (j = 0; j < imu->nr_bvecs; j++) {
--
2.39.2
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