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libceph: fix overflow in __decode_pool_names()

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`len' is read from network and thus needs validation.  Otherwise a
large `len' would cause out-of-bounds access via the memcpy() call.
In addition, len = 0xffffffff would overflow the kmalloc() size,
leading to out-of-bounds write.

This patch adds a check of `len' via ceph_decode_need().  Also use
kstrndup rather than kmalloc/memcpy.

[elder@inktank.com: added -ENOMEM return for null kstrndup() result]

Signed-off-by: Xi Wang <xi.wang@gmail.com>
Reviewed-by: Alex Elder <elder@inktank.com>
This commit is contained in:
Xi Wang 2012-06-06 19:35:55 -05:00 committed by Alex Elder
parent 43643528cc
commit ad3b904c07
1 changed files with 7 additions and 6 deletions
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13
net/ceph/osdmap.c
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@ -488,15 +488,16 @@ static int __decode_pool_names(void **p, void *end, struct ceph_osdmap *map)
ceph_decode_32_safe(p, end, pool, bad);
ceph_decode_32_safe(p, end, len, bad);
dout(" pool %d len %d\n", pool, len);
ceph_decode_need(p, end, len, bad);
pi = __lookup_pg_pool(&map->pg_pools, pool);
if (pi) {
char *name = kstrndup(*p, len, GFP_NOFS);
if (!name)
return -ENOMEM;
kfree(pi->name);
pi->name = kmalloc(len + 1, GFP_NOFS);
if (pi->name) {
memcpy(pi->name, *p, len);
pi->name[len] = '\0';
dout(" name is %s\n", pi->name);
}
pi->name = name;
dout(" name is %s\n", pi->name);
}
*p += len;
}