The original checks (via sk_chk_filter) for instruction count uses ">",
not ">=", so changing this in sk_convert_filter has the potential to break
existing seccomp filters that used exactly BPF_MAXINSNS many instructions.
Fixes: bd4cf0ed331a ("net: filter: rework/optimize internal BPF interpreter's
instruction set")
Signed-off-by: Kees Cook <[email protected]>
Cc: [email protected] # v3.15+
---
net/core/filter.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index 735fad897496..a44e12cdde4c 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -840,7 +840,7 @@ int sk_convert_filter(struct sock_filter *prog, int len,
BUILD_BUG_ON(BPF_MEMWORDS * sizeof(u32) > MAX_BPF_STACK);
BUILD_BUG_ON(BPF_REG_FP + 1 != MAX_BPF_REG);
- if (len <= 0 || len >= BPF_MAXINSNS)
+ if (len <= 0 || len > BPF_MAXINSNS)
return -EINVAL;
if (new_prog) {
--
1.7.9.5
--
Kees Cook
Chrome OS Security
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