diff mbox series

[3/3] bpf: Propagate error from htab_lock_bucket() to userspace

Message ID 20220821033223.2598791-4-houtao@huaweicloud.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series fixes for concurrent htab updates | expand

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netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 348 this patch: 348
netdev/cc_maintainers warning 2 maintainers not CCed: song@kernel.org martin.lau@linux.dev
netdev/build_clang success Errors and warnings before: 5 this patch: 5
netdev/module_param success Was 0 now: 0
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netdev/verify_fixes success No Fixes tag
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Commit Message

Hou Tao Aug. 21, 2022, 3:32 a.m. UTC 
From: Hou Tao <houtao1@huawei.com>

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.

Reported-by: Hao Sun <sunhao.th@gmail.com>
Signed-off-by: Hou Tao <houtao1@huawei.com>
---
 kernel/bpf/hashtab.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 3ef7a853c737..ffd39048e6da 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -1711,8 +1711,11 @@  __htab_map_lookup_and_delete_batch(struct bpf_map *map,
 	/* 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;