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[bpf-next] libbpf: Fix out-of-bound read

Message ID 20250221210110.3182084-1-nandakumar@nandakumar.co.in (mailing list archive)
State New
Delegated to: BPF
Headers show
Series [bpf-next] libbpf: Fix out-of-bound read | expand

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netdev/series_format success Single patches do not need cover letters
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netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
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/build_tools success Errors and warnings before: 26 (+1) this patch: 26 (+1)
netdev/cc_maintainers warning 11 maintainers not CCed: ast@kernel.org kpsingh@kernel.org daniel@iogearbox.net sdf@fomichev.me jolsa@kernel.org yonghong.song@linux.dev andrii@kernel.org song@kernel.org john.fastabend@gmail.com haoluo@google.com martin.lau@linux.dev
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Commit Message

Nandakumar Edamana Feb. 21, 2025, 9:01 p.m. UTC 
In `set_kcfg_value_str`, an untrusted string is accessed with the assumption
that it will be at least two characters long due to the presence of checks for
opening and closing quotes. But the check for the closing quote
(value[len - 1] != '"') misses the fact that it could be checking the opening
quote itself in case of an invalid input that consists of just the opening
quote.

This commit adds an explicit check to make sure the string is at least two
characters long.

Signed-off-by: Nandakumar Edamana <nandakumar@nandakumar.co.in>
---
 tools/lib/bpf/libbpf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 194809da5172..1cc87dbd015d 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2106,7 +2106,7 @@  static int set_kcfg_value_str(struct extern_desc *ext, char *ext_val,
 	}
 
 	len = strlen(value);
-	if (value[len - 1] != '"') {
+	if (len < 2 || value[len - 1] != '"') {
 		pr_warn("extern (kcfg) '%s': invalid string config '%s'\n",
 			ext->name, value);
 		return -EINVAL;