arm64: csum: Fix handling of bad packets
Although iph is expected to point to at least 20 bytes of valid memory,
ihl may be bogus, for example on reception of a corrupt packet. If it
happens to be less than 5, we really don't want to run away and
dereference 16GB worth of memory until it wraps back to exactly zero...
Fixes: 0e455d8e80aa ("arm64: Implement optimised IP checksum helpers")
Reported-by: guodeqing <geffrey.guo@huawei.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
diff --git a/arch/arm64/include/asm/checksum.h b/arch/arm64/include/asm/checksum.h
index b6f7bc6..93a161b 100644
--- a/arch/arm64/include/asm/checksum.h
+++ b/arch/arm64/include/asm/checksum.h
@@ -24,16 +24,17 @@
{
__uint128_t tmp;
u64 sum;
+ int n = ihl; /* we want it signed */
tmp = *(const __uint128_t *)iph;
iph += 16;
- ihl -= 4;
+ n -= 4;
tmp += ((tmp >> 64) | (tmp << 64));
sum = tmp >> 64;
do {
sum += *(const u32 *)iph;
iph += 4;
- } while (--ihl);
+ } while (--n > 0);
sum += ((sum >> 32) | (sum << 32));
return csum_fold((__force u32)(sum >> 32));
