5.4-stable review patch. If anyone has any objections, please let me know.
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From: John Fastabend john.fastabend@gmail.com
[ Upstream commit bb9aefde5bbaf6c168c77ba635c155b4980c2287 ]
Curr pointer should be updated when the sg structure is shifted.
Fixes: 7246d8ed4dcce ("bpf: helper to pop data from messages") Signed-off-by: John Fastabend john.fastabend@gmail.com Link: https://lore.kernel.org/r/20231206232706.374377-3-john.fastabend@gmail.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/filter.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)
diff --git a/net/core/filter.c b/net/core/filter.c index d866e1c5970cc..3c4dcdc7217e0 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2219,6 +2219,22 @@ BPF_CALL_2(bpf_msg_cork_bytes, struct sk_msg *, msg, u32, bytes) return 0; }
+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); + + msg->sg.curr = i; + msg->sg.copybreak = 0; +} + static const struct bpf_func_proto bpf_msg_cork_bytes_proto = { .func = bpf_msg_cork_bytes, .gpl_only = false, @@ -2338,6 +2354,7 @@ BPF_CALL_4(bpf_msg_pull_data, struct sk_msg *, msg, u32, start, msg->sg.end - shift + NR_MSG_FRAG_IDS : msg->sg.end - shift; out: + sk_msg_reset_curr(msg); msg->data = sg_virt(&msg->sg.data[first_sge]) + start - offset; msg->data_end = msg->data + bytes; return 0; @@ -2471,6 +2488,7 @@ BPF_CALL_4(bpf_msg_push_data, struct sk_msg *, msg, u32, start, msg->sg.data[new] = rsge; }
+ sk_msg_reset_curr(msg); sk_msg_compute_data_pointers(msg); return 0; } @@ -2642,6 +2660,7 @@ BPF_CALL_4(bpf_msg_pop_data, struct sk_msg *, msg, u32, start,
sk_mem_uncharge(msg->sk, len - pop); msg->sg.size -= (len - pop); + sk_msg_reset_curr(msg); sk_msg_compute_data_pointers(msg); return 0; }