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apparmor: enforce nullbyte at end of tag string

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A packed AppArmor policy contains null-terminated tag strings that are read
by unpack_nameX(). However, unpack_nameX() uses string functions on them
without ensuring that they are actually null-terminated, potentially
leading to out-of-bounds accesses.

Make sure that the tag string is null-terminated before passing it to
strcmp().

Cc: stable@vger.kernel.org
Fixes: 736ec752d95e ("AppArmor: policy routines for loading and unpacking policy")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
This commit is contained in:
Jann Horn 2019-05-28 17:32:26 +02:00 committed by John Johansen
parent 23375b13f9
commit 8404d7a674
1 changed files with 1 additions and 1 deletions
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2
security/apparmor/policy_unpack.c
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@ -272,7 +272,7 @@ static bool unpack_nameX(struct aa_ext *e, enum aa_code code, const char *name)
char *tag = NULL;
size_t size = unpack_u16_chunk(e, &tag);
/* if a name is specified it must match. otherwise skip tag */
if (name && (!size || strcmp(name, tag)))
if (name && (!size || tag[size-1] != '\0' || strcmp(name, tag)))
goto fail;
} else if (name) {
/* if a name is specified and there is no name tag fail */