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Commit 2f40a178 authored by Joy Latten's avatar Joy Latten Committed by Herbert Xu
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[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 <latten@austin.ibm.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 6212f2c7

crypto/xcbc.c

+5 −1
Original line number Original line Diff line number Diff line
@@ -124,6 +124,11 @@ static int crypto_xcbc_digest_update2(struct hash_desc *pdesc, 
		unsigned int offset = sg[i].offset;

		unsigned int offset = sg[i].offset;

		unsigned int slen = sg[i].length;

		unsigned int slen = sg[i].length;





		if (unlikely(slen > nbytes))

			slen = nbytes;



		nbytes -= slen;



		while (slen > 0) {

		while (slen > 0) {

			unsigned int len = min(slen, ((unsigned int)(PAGE_SIZE)) - offset);

			unsigned int len = min(slen, ((unsigned int)(PAGE_SIZE)) - offset);

			char *p = crypto_kmap(pg, 0) + offset;

			char *p = crypto_kmap(pg, 0) + offset;
@@ -177,7 +182,6 @@ static int crypto_xcbc_digest_update2(struct hash_desc *pdesc, 
			offset = 0;

			offset = 0;

			pg++;

			pg++;

		}

		}

		nbytes-=sg[i].length;

		i++;

		i++;

	} while (nbytes>0);

	} while (nbytes>0);