diff mbox series

[bpf] libbpf: fix overflow in BTF sanity checks

Message ID 20211019165801.88714-1-andrii@kernel.org (mailing list archive)
State Accepted
Delegated to: BPF
Headers show
Series [bpf] libbpf: fix overflow in BTF sanity checks | expand

Checks

Context Check Description
netdev/cover_letter success Single patches do not need cover letters
netdev/fixes_present success Fixes tag present in non-next series
netdev/patch_count success Link
netdev/tree_selection success Clearly marked for bpf
netdev/subject_prefix success Link
netdev/cc_maintainers warning 6 maintainers not CCed: john.fastabend@gmail.com yhs@fb.com netdev@vger.kernel.org songliubraving@fb.com kafai@fb.com kpsingh@kernel.org
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/verify_fixes success Fixes tag looks correct
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 14 lines checked
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/header_inline success No static functions without inline keyword in header files
bpf/vmtest-bpf success VM_Test
bpf/vmtest-bpf-PR success PR summary

Commit Message

Andrii Nakryiko Oct. 19, 2021, 4:58 p.m. UTC 
From: Andrii Nakryiko <andrii@kernel.org>

btf_header's str_off+str_len or type_off+type_len can overflow as they
are u32s. This will lead to bypassing the sanity checks during BTF
parsing, resulting in crashes afterwards. Fix by using 64-bit signed
integers for comparison.

Fixes: d8123624506c ("libbpf: Fix BTF data layout checks and allow empty BTF")
Reported-by: Evgeny Vereshchagin <evvers@ya.ru>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/lib/bpf/btf.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Alexei Starovoitov Oct. 21, 2021, 1:14 a.m. UTC | #1 
On Tue, Oct 19, 2021 at 9:58 AM <andrii.nakryiko@gmail.com> wrote:
>
> From: Andrii Nakryiko <andrii@kernel.org>
>
> btf_header's str_off+str_len or type_off+type_len can overflow as they
> are u32s. This will lead to bypassing the sanity checks during BTF
> parsing, resulting in crashes afterwards. Fix by using 64-bit signed
> integers for comparison.
>
> Fixes: d8123624506c ("libbpf: Fix BTF data layout checks and allow empty BTF")
> Reported-by: Evgeny Vereshchagin <evvers@ya.ru>
> Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

Applied.
diff mbox series

Patch

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 1f6dea11f600..7ed117401e52 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -241,12 +241,12 @@  static int btf_parse_hdr(struct btf *btf)
 	}
 
 	meta_left = btf->raw_size - sizeof(*hdr);
-	if (meta_left < hdr->str_off + hdr->str_len) {
+	if (meta_left < (long long)hdr->str_off + hdr->str_len) {
 		pr_debug("Invalid BTF total size:%u\n", btf->raw_size);
 		return -EINVAL;
 	}
 
-	if (hdr->type_off + hdr->type_len > hdr->str_off) {
+	if ((long long)hdr->type_off + hdr->type_len > hdr->str_off) {
 		pr_debug("Invalid BTF data sections layout: type data at %u + %u, strings data at %u + %u\n",
 			 hdr->type_off, hdr->type_len, hdr->str_off, hdr->str_len);
 		return -EINVAL;