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| author | Jens Axboe <axboe@kernel.dk> | 2024-11-29 15:20:28 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2024-11-29 15:20:28 +0100 |
| commit | 7eb75ce7527129d7f1fee6951566af409a37a1c4 (patch) | |
| tree | 91a2fd805f90410062190d2a6d12cbaca1cf37ce /io_uring | |
| parent | io_uring: fix corner case forgetting to vunmap (diff) | |
| download | linux-7eb75ce7527129d7f1fee6951566af409a37a1c4.tar.xz linux-7eb75ce7527129d7f1fee6951566af409a37a1c4.zip | |
io_uring/tctx: work around xa_store() allocation error issue
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>
Diffstat (limited to 'io_uring')
| -rw-r--r-- | io_uring/tctx.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/io_uring/tctx.c b/io_uring/tctx.c index 503f3ff8bc4f..adc6e42c14df 100644 --- a/io_uring/tctx.c +++ b/io_uring/tctx.c @@ -47,8 +47,19 @@ static struct io_wq *io_init_wq_offload(struct io_ring_ctx *ctx, 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); |