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crypto: krb5 - Use SG miter instead of doing it by hand

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The function crypto_shash_update_sg iterates through an SG by
hand.  It fails to handle corner cases such as SG entries longer
than a page.  Fix this by using the SG iterator.

Fixes: 348f5669d1 ("crypto/krb5: Implement the Kerberos5 rfc3961 get_mic and verify_mic")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Herbert Xu 2025-03-13 13:14:56 +08:00
parent fc8d5bba61
commit da6f9bf40a
1 changed files with 15 additions and 20 deletions
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31
crypto/krb5/rfc3961_simplified.c
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@ -67,9 +67,9 @@
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/random.h>
#include <linux/scatterlist.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/highmem.h>
#include <linux/lcm.h>
#include <linux/rtnetlink.h>
#include <crypto/authenc.h>
@ -83,26 +83,21 @@
int crypto_shash_update_sg(struct shash_desc *desc, struct scatterlist *sg,
size_t offset, size_t len)
{
do {
int ret;
struct sg_mapping_iter miter;
size_t i, n;
int ret = 0;
if (offset < sg->length) {
struct page *page = sg_page(sg);
void *p = kmap_local_page(page);
void *q = p + sg->offset + offset;
size_t seg = min_t(size_t, len, sg->length - offset);
ret = crypto_shash_update(desc, q, seg);
kunmap_local(p);
sg_miter_start(&miter, sg, sg_nents(sg),
SG_MITER_FROM_SG | SG_MITER_LOCAL);
for (i = 0; i < len; i += n) {
sg_miter_next(&miter);
n = min(miter.length, len - i);
ret = crypto_shash_update(desc, miter.addr, n);
if (ret < 0)
return ret;
len -= seg;
offset = 0;
} else {
offset -= sg->length;
break;
}
} while (len > 0 && (sg = sg_next(sg)));
return 0;
sg_miter_stop(&miter);
return ret;
}
static int rfc3961_do_encrypt(struct crypto_sync_skcipher *tfm, void *iv,