diff mbox series

[bpf,v2,3/4] libbpf: Handle size overflow for user ringbuf mmap

Message ID 20221116072351.1168938-4-houtao@huaweicloud.com (mailing list archive)
State Accepted
Commit 64176bff2446cd825b163976ee451fb6e5cd851d
Delegated to: BPF
Headers show
Series libbpf: Fixes for ring buffer | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for bpf
netdev/fixes_present success Fixes tag present in non-next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/cc_maintainers success CCed 13 of 13 maintainers
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
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netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 23 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
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bpf/vmtest-bpf-PR success PR summary

Commit Message

Hou Tao Nov. 16, 2022, 7:23 a.m. UTC 
From: Hou Tao <houtao1@huawei.com>

Similar with the overflow problem on ringbuf mmap, in user_ringbuf_map()
2 * max_entries may overflow u32 when mapping writeable region.

Fixing it by casting the size of writable mmap region into a __u64 and
checking whether or not there will be overflow during mmap.

Fixes: b66ccae01f1d ("bpf: Add libbpf logic for user-space ring buffer")
Signed-off-by: Hou Tao <houtao1@huawei.com>
---
 tools/lib/bpf/ringbuf.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/tools/lib/bpf/ringbuf.c b/tools/lib/bpf/ringbuf.c
index 5b1dc8794b06..277e49137a95 100644
--- a/tools/lib/bpf/ringbuf.c
+++ b/tools/lib/bpf/ringbuf.c
@@ -355,6 +355,7 @@  static int user_ringbuf_map(struct user_ring_buffer *rb, int map_fd)
 {
 	struct bpf_map_info info;
 	__u32 len = sizeof(info);
+	__u64 mmap_sz;
 	void *tmp;
 	struct epoll_event *rb_epoll;
 	int err;
@@ -391,8 +392,14 @@  static int user_ringbuf_map(struct user_ring_buffer *rb, int map_fd)
 	 * simple reading and writing of samples that wrap around the end of
 	 * the buffer.  See the kernel implementation for details.
 	 */
-	tmp = mmap(NULL, rb->page_size + 2 * info.max_entries,
-		   PROT_READ | PROT_WRITE, MAP_SHARED, map_fd, rb->page_size);
+	mmap_sz = rb->page_size + 2 * (__u64)info.max_entries;
+	if (mmap_sz != (__u64)(size_t)mmap_sz) {
+		pr_warn("user ringbuf: ring buf size (%u) is too big\n",
+			info.max_entries);
+		return -E2BIG;
+	}
+	tmp = mmap(NULL, (size_t)mmap_sz, PROT_READ | PROT_WRITE, MAP_SHARED,
+		   map_fd, rb->page_size);
 	if (tmp == MAP_FAILED) {
 		err = -errno;
 		pr_warn("user ringbuf: failed to mmap data pages for map fd=%d: %d\n",