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| author | Hou Tao <houtao1@huawei.com> | 2022-08-31 06:26:28 +0200 |
|---|---|---|
| committer | Martin KaFai Lau <martin.lau@kernel.org> | 2022-08-31 23:10:01 +0200 |
| commit | 66a7a92e4d0d091e79148a4c6ec15d1da65f4280 (patch) | |
| tree | 98ec0e1fb6c9359d6b586aa44ea44b4309f74f23 /kernel/bpf | |
| parent | bpf: Disable preemption when increasing per-cpu map_locked (diff) | |
| download | linux-66a7a92e4d0d091e79148a4c6ec15d1da65f4280.tar.xz linux-66a7a92e4d0d091e79148a4c6ec15d1da65f4280.zip | |
bpf: Propagate error from htab_lock_bucket() to userspace
In __htab_map_lookup_and_delete_batch() if htab_lock_bucket() returns
-EBUSY, it will go to next bucket. Going to next bucket may not only
skip the elements in current bucket silently, but also incur
out-of-bound memory access or expose kernel memory to userspace if
current bucket_cnt is greater than bucket_size or zero.
Fixing it by stopping batch operation and returning -EBUSY when
htab_lock_bucket() fails, and the application can retry or skip the busy
batch as needed.
Fixes: 20b6cc34ea74 ("bpf: Avoid hashtab deadlock with map_locked")
Reported-by: Hao Sun <sunhao.th@gmail.com>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20220831042629.130006-3-houtao@huaweicloud.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/hashtab.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index 6fb3b7fd1622..eb1263f03e9b 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -1704,8 +1704,11 @@ again_nocopy: /* do not grab the lock unless need it (bucket_cnt > 0). */ if (locked) { ret = htab_lock_bucket(htab, b, batch, &flags); - if (ret) - goto next_batch; + if (ret) { + rcu_read_unlock(); + bpf_enable_instrumentation(); + goto after_loop; + } } bucket_cnt = 0; |