[PATCH 4.19 059/114] apparmor: fix unsigned len comparison with less than zero

Greg Kroah-Hartman
2020-01-02T22:20:58Z

From: Colin Ian King <colin.king@canonical.com>

[ Upstream commit 00e0590dbaec6f1bcaa36a85467d7e3497ced522 ]

The sanity check in macro update_for_len checks to see if len
is less than zero, however, len is a size_t so it can never be
less than zero, so this sanity check is a no-op. Fix this by
making len a ssize_t so the comparison will work and add ulen
that is a size_t copy of len so that the min() macro won't
throw warnings about comparing different types.

Addresses-Coverity: ("Macro compares unsigned to 0")
Fixes: f1bd904175e8 ("apparmor: add the base fns() for domain labels")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
security/apparmor/label.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/security/apparmor/label.c b/security/apparmor/label.c
index ba11bdf9043a..2469549842d2 100644
--- a/security/apparmor/label.c
+++ b/security/apparmor/label.c
@@ -1462,11 +1462,13 @@ static inline bool use_label_hname(struct aa_ns *ns, struct aa_label *label,
/* helper macro for snprint routines */
#define update_for_len(total, len, size, str) \
do { \
+ size_t ulen = len; \
+ \
AA_BUG(len < 0); \
- total += len; \
- len = min(len, size); \
- size -= len; \
- str += len; \
+ total += ulen; \
+ ulen = min(ulen, size); \
+ size -= ulen; \
+ str += ulen; \
} while (0)

/**
@@ -1601,7 +1603,7 @@ int aa_label_snxprint(char *str, size_t size, struct aa_ns *ns,
struct aa_ns *prev_ns = NULL;
struct label_it i;
int count = 0, total = 0;
- size_t len;
+ ssize_t len;

AA_BUG(!str && size != 0);
AA_BUG(!label);
--
2.20.1