diff options
| author | Hou Tao <houtao1@huawei.com> | 2024-03-12 03:44:35 +0300 |
|---|---|---|
| committer | Sasha Levin <sashal@kernel.org> | 2024-03-27 01:21:45 +0300 |
| commit | 90c445799fd1dc214d7c6279c144e33a35e29ef2 (patch) | |
| tree | 0ef4eb3c565b80370d2b30928f78bcd7f9b0b5aa /include/linux/bpf.h | |
| parent | 93c37f1c63b453d24f0101fb58e7f4bb8bab9d83 (diff) | |
| download | linux-90c445799fd1dc214d7c6279c144e33a35e29ef2.tar.xz | |
bpf: Defer the free of inner map when necessary
[ Upstream commit 876673364161da50eed6b472d746ef88242b2368 ]
When updating or deleting an inner map in map array or map htab, the map
may still be accessed by non-sleepable program or sleepable program.
However bpf_map_fd_put_ptr() decreases the ref-counter of the inner map
directly through bpf_map_put(), if the ref-counter is the last one
(which is true for most cases), the inner map will be freed by
ops->map_free() in a kworker. But for now, most .map_free() callbacks
don't use synchronize_rcu() or its variants to wait for the elapse of a
RCU grace period, so after the invocation of ops->map_free completes,
the bpf program which is accessing the inner map may incur
use-after-free problem.
Fix the free of inner map by invoking bpf_map_free_deferred() after both
one RCU grace period and one tasks trace RCU grace period if the inner
map has been removed from the outer map before. The deferment is
accomplished by using call_rcu() or call_rcu_tasks_trace() when
releasing the last ref-counter of bpf map. The newly-added rcu_head
field in bpf_map shares the same storage space with work field to
reduce the size of bpf_map.
Fixes: bba1dc0b55ac ("bpf: Remove redundant synchronize_rcu.")
Fixes: 638e4b825d52 ("bpf: Allows per-cpu maps and map-in-map in sleepable programs")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20231204140425.1480317-5-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
(cherry picked from commit 62fca83303d608ad4fec3f7428c8685680bb01b0)
Signed-off-by: Robert Kolchmeyer <rkolchmeyer@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'include/linux/bpf.h')
| -rw-r--r-- | include/linux/bpf.h | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index bfdf40be5360..a75faf437e75 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -175,9 +175,14 @@ struct bpf_map { */ atomic64_t refcnt ____cacheline_aligned; atomic64_t usercnt; - struct work_struct work; + /* rcu is used before freeing and work is only used during freeing */ + union { + struct work_struct work; + struct rcu_head rcu; + }; struct mutex freeze_mutex; atomic64_t writecnt; + bool free_after_mult_rcu_gp; }; static inline bool map_value_has_spin_lock(const struct bpf_map *map) |