On Fri, May 20, 2022 at 11:01:22AM +0200, Stefano Brivio wrote:
In conf_runas(), Coverity reports that we might
dereference uid and
gid despite possibly being NULL (CWE-476) because of the check after
the first sscanf(). They can't be NULL, but I actually wanted to
check that UID and GID are non-zero (the user could otherwise pass
--runas root:root and defy the whole mechanism).
Later on, we have the same type of warning for 'gr': it's compared
against NULL, so it might be NULL, which is actually the case: but
in that case, we don't dereference it, because we'll return -ENOENT
right away. Rewrite the clause to silence the warning.
Signed-off-by: Stefano Brivio <sbrivio(a)redhat.com>
Reviewed-by: David Gibson <david(a)gibson.dropbear.id.au>
---
conf.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/conf.c b/conf.c
index ddad9a3..d615cf5 100644
--- a/conf.c
+++ b/conf.c
@@ -857,7 +857,7 @@ static int conf_runas(const char *opt, unsigned int *uid, unsigned
int *gid)
struct group *gr;
/* NOLINTNEXTLINE(cert-err34-c): 2 if conversion succeeds */
- if (sscanf(opt, "%u:%u", uid, gid) == 2 && uid && gid)
+ if (sscanf(opt, "%u:%u", uid, gid) == 2 && *uid && *gid)
return 0;
*uid = strtol(opt, &endptr, 0);
@@ -874,12 +874,10 @@ static int conf_runas(const char *opt, unsigned int *uid, unsigned
int *gid)
/* NOLINTNEXTLINE(cert-err34-c): 2 if conversion succeeds */
if (sscanf(opt, "%" STR(LOGIN_NAME_MAX) "[^:]:"
"%" STR(LOGIN_NAME_MAX) "s", ubuf, gbuf) == 2) {
- pw = getpwnam(ubuf);
- if (!pw || !(*uid = pw->pw_uid))
+ if (!(pw = getpwnam(ubuf)) || !(*uid = pw->pw_uid))
return -ENOENT;
- gr = getgrnam(gbuf);
- if (!gr || !(*gid = gr->gr_gid))
+ if (!(gr = getgrnam(gbuf)) || !(*gid = gr->gr_gid))
return -ENOENT;
return 0;
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson