From: Jens Axboe axboe@kernel.dk

mainline inclusion from mainline-v6.10-rc2 commit 7eb75ce7527129d7f1fee6951566af409a37a1c4 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBEAP3 CVE: CVE-2024-56584

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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syzbot triggered the following WARN_ON:

WARNING: CPU: 0 PID: 16 at io_uring/tctx.c:51 __io_uring_free+0xfa/0x140 io_uring/tctx.c:51

which is the

WARN_ON_ONCE(!xa_empty(&tctx->xa));

sanity check in __io_uring_free() when a io_uring_task is going through its final put. The syzbot test case includes injecting memory allocation failures, and it very much looks like xa_store() can fail one of its memory allocations and end up with ->head being non-NULL even though no entries exist in the xarray.

Until this issue gets sorted out, work around it by attempting to iterate entries in our xarray, and WARN_ON_ONCE() if one is found.

Reported-by: syzbot+cc36d44ec9f368e443d3@syzkaller.appspotmail.com Link: https://lore.kernel.org/io-uring/673c1643.050a0220.87769.0066.GAE@google.com... Signed-off-by: Jens Axboe axboe@kernel.dk Conflicts: io_uring/io_uring.c io_uring/tctx.c [Conflicts due to __io_uring_free() move to io_uring/tctx.c in mainline] Signed-off-by: Long Li leo.lilong@huawei.com --- io_uring/io_uring.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 4d69fb4cf803..e058ce8bb8e2 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -8341,8 +8341,19 @@ static int io_uring_alloc_task_context(struct task_struct *task, void __io_uring_free(struct task_struct *tsk) { struct io_uring_task *tctx = tsk->io_uring; + struct io_tctx_node *node; + unsigned long index;

- WARN_ON_ONCE(!xa_empty(&tctx->xa)); + /* + * Fault injection forcing allocation errors in the xa_store() path + * can lead to xa_empty() returning false, even though no actual + * node is stored in the xarray. Until that gets sorted out, attempt + * an iteration here and warn if any entries are found. + */ + xa_for_each(&tctx->xa, index, node) { + WARN_ON_ONCE(1); + break; + } WARN_ON_ONCE(tctx->io_wq); WARN_ON_ONCE(tctx->cached_refs);