Commit 2f40a178 authored by Joy Latten's avatar Joy Latten Committed by Herbert Xu

[CRYPTO] xcbc: Fix crash with IPsec

When using aes-xcbc-mac for authentication in IPsec, 
the kernel crashes. It seems this algorithm doesn't 
account for the space IPsec may make in scatterlist for authtag.
Thus when crypto_xcbc_digest_update2() gets called,
nbytes may be less than sg[i].length. 
Since nbytes is an unsigned number, it wraps
at the end of the loop allowing us to go back 
into loop and causing crash in memcpy.

I used update function in digest.c to model this fix.
Please let me know if it looks ok.
Signed-off-by: default avatarJoy Latten <>
Signed-off-by: default avatarHerbert Xu <>
parent 6212f2c7
......@@ -124,6 +124,11 @@ static int crypto_xcbc_digest_update2(struct hash_desc *pdesc,
unsigned int offset = sg[i].offset;
unsigned int slen = sg[i].length;
if (unlikely(slen > nbytes))
slen = nbytes;
nbytes -= slen;
while (slen > 0) {
unsigned int len = min(slen, ((unsigned int)(PAGE_SIZE)) - offset);
char *p = crypto_kmap(pg, 0) + offset;
......@@ -177,7 +182,6 @@ static int crypto_xcbc_digest_update2(struct hash_desc *pdesc,
offset = 0;
} while (nbytes>0);
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