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libbpf: Refactor cleanup in ring_buffer__add

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Refactor the cleanup code in ring_buffer__add to use a unified err_out
label. This reduces code duplication, as well as plugging a potential
leak if mmap_sz != (__u64)(size_t)mmap_sz (currently this would miss
unmapping tmp because ringbuf_unmap_ring isn't called).

Signed-off-by: Martin Kelly <martin.kelly@crowdstrike.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230925215045.2375758-2-martin.kelly@crowdstrike.com
This commit is contained in:
Martin Kelly 2023-09-25 14:50:32 -07:00 committed by Andrii Nakryiko
parent 831916fb93
commit 4448f64c54
1 changed files with 9 additions and 6 deletions
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15
tools/lib/bpf/ringbuf.c
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@ -121,7 +121,7 @@ int ring_buffer__add(struct ring_buffer *rb, int map_fd,
err = -errno;
pr_warn("ringbuf: failed to mmap consumer page for map fd=%d: %d\n",
map_fd, err);
return libbpf_err(err);
goto err_out;
}
r->consumer_pos = tmp;
@ -131,16 +131,16 @@ int ring_buffer__add(struct ring_buffer *rb, int map_fd,
*/
mmap_sz = rb->page_size + 2 * (__u64)info.max_entries;
if (mmap_sz != (__u64)(size_t)mmap_sz) {
err = -E2BIG;
pr_warn("ringbuf: ring buffer size (%u) is too big\n", info.max_entries);
return libbpf_err(-E2BIG);
goto err_out;
}
tmp = mmap(NULL, (size_t)mmap_sz, PROT_READ, MAP_SHARED, map_fd, rb->page_size);
if (tmp == MAP_FAILED) {
err = -errno;
ringbuf_unmap_ring(rb, r);
pr_warn("ringbuf: failed to mmap data pages for map fd=%d: %d\n",
map_fd, err);
return libbpf_err(err);
goto err_out;
}
r->producer_pos = tmp;
r->data = tmp + rb->page_size;
@ -152,14 +152,17 @@ int ring_buffer__add(struct ring_buffer *rb, int map_fd,
e->data.fd = rb->ring_cnt;
if (epoll_ctl(rb->epoll_fd, EPOLL_CTL_ADD, map_fd, e) < 0) {
err = -errno;
ringbuf_unmap_ring(rb, r);
pr_warn("ringbuf: failed to epoll add map fd=%d: %d\n",
map_fd, err);
return libbpf_err(err);
goto err_out;
}
rb->ring_cnt++;
return 0;
err_out:
ringbuf_unmap_ring(rb, r);
return libbpf_err(err);
}
void ring_buffer__free(struct ring_buffer *rb)