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bpf, sockmap: Fix sk_msg_reset_curr

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[ 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>
This commit is contained in:
Zijian Zhang 2024-11-06 22:25:20 +00:00 committed by Greg Kroah-Hartman
parent f58d3aa457
commit 9610b69033
1 changed files with 9 additions and 11 deletions
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20
net/core/filter.c
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@ -2594,18 +2594,16 @@ 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;
if (!msg->sg.size) {
msg->sg.curr = msg->sg.start;
msg->sg.copybreak = 0;
} else {
u32 i = msg->sg.end;
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);
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 = {