From 3983c00281d96af2ba611254d679107b5c390627 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Sun, 17 Dec 2023 22:55:37 +0100 Subject: [PATCH] bpf: Fail uprobe multi link with negative offset Currently the __uprobe_register will return 0 (success) when called with negative offset. The reason is that the call to register_for_each_vma and then build_map_info won't return error for negative offset. They just won't do anything - no matching vma is found so there's no registered breakpoint for the uprobe. I don't think we can change the behaviour of __uprobe_register and fail for negative uprobe offset, because apps might depend on that already. But I think we can still make the change and check for it on bpf multi link syscall level. Also moving the __get_user call and check for the offsets to the top of loop, to fail early without extra __get_user calls for ref_ctr_offset and cookie arrays. Signed-off-by: Jiri Olsa Signed-off-by: Andrii Nakryiko Acked-by: Song Liu Link: https://lore.kernel.org/bpf/20231217215538.3361991-2-jolsa@kernel.org --- kernel/trace/bpf_trace.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 97c0c49c40a02..492d60e9c4800 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -3391,15 +3391,19 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr goto error_free; for (i = 0; i < cnt; i++) { - if (ucookies && __get_user(uprobes[i].cookie, ucookies + i)) { + if (__get_user(uprobes[i].offset, uoffsets + i)) { err = -EFAULT; goto error_free; } + if (uprobes[i].offset < 0) { + err = -EINVAL; + goto error_free; + } if (uref_ctr_offsets && __get_user(uprobes[i].ref_ctr_offset, uref_ctr_offsets + i)) { err = -EFAULT; goto error_free; } - if (__get_user(uprobes[i].offset, uoffsets + i)) { + if (ucookies && __get_user(uprobes[i].cookie, ucookies + i)) { err = -EFAULT; goto error_free; } -- 2.30.2