6.12-stable review patch. If anyone has any objections, please let me know.
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From: Zijian Zhang zijianzhang@bytedance.com
[ Upstream commit 955afd57dc4bf7e8c620a0a9e3af3c881c2c6dff ]
Found in the test_txmsg_pull in test_sockmap, ``` txmsg_cork = 512; // corking is importrant here opt->iov_length = 3; opt->iov_count = 1; opt->rate = 512; // sendmsg will be invoked 512 times ``` The first sendmsg will send an sk_msg with size 3, and bpf_msg_pull_data will be invoked the first time. sk_msg_reset_curr will reset the copybreak from 3 to 0. In the second sendmsg, since we are in the stage of corking, psock->cork will be reused in func sk_msg_alloc. msg->sg.copybreak is 0 now, the second msg will overwrite the first msg. As a result, we could not pass the data integrity test.
The same problem happens in push and pop test. Thus, fix sk_msg_reset_curr to restore the correct copybreak.
Fixes: bb9aefde5bba ("bpf: sockmap, updating the sg structure should also update curr") Signed-off-by: Zijian Zhang zijianzhang@bytedance.com Link: https://lore.kernel.org/r/20241106222520.527076-9-zijianzhang@bytedance.com Signed-off-by: Martin KaFai Lau martin.lau@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/filter.c | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-)
diff --git a/net/core/filter.c b/net/core/filter.c index 60c6e1e4662bd..9a459213d283f 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2621,18 +2621,16 @@ BPF_CALL_2(bpf_msg_cork_bytes, struct sk_msg *, msg, u32, bytes)
static void sk_msg_reset_curr(struct sk_msg *msg) { - u32 i = msg->sg.start; - u32 len = 0; - - do { - len += sk_msg_elem(msg, i)->length; - sk_msg_iter_var_next(i); - if (len >= msg->sg.size) - break; - } while (i != msg->sg.end); + if (!msg->sg.size) { + msg->sg.curr = msg->sg.start; + msg->sg.copybreak = 0; + } else { + u32 i = msg->sg.end;
- msg->sg.curr = i; - msg->sg.copybreak = 0; + sk_msg_iter_var_prev(i); + msg->sg.curr = i; + msg->sg.copybreak = msg->sg.data[i].length; + } }
static const struct bpf_func_proto bpf_msg_cork_bytes_proto = {