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[PULL,13/16] linux-user: Return EINVAL for getgroups() with negative gidsetsize

Message ID 8fbf89a9669520ac09b3ae0013ff3eb34f8cab23.1686379708.git.mjt@tls.msk.ru
State New
Headers show
Series [PULL,01/16] docs: Fix trivial typos in vhost-user.rst | expand

Commit Message

Michael Tokarev June 10, 2023, 6:57 a.m. UTC 
From: Peter Maydell <peter.maydell@linaro.org>

Coverity doesn't like the way we might end up calling getgroups()
with a NULL grouplist pointer. This is fine for the special case
of gidsetsize == 0, but we will also do it if the guest passes
us a negative gidsetsize. (CID 1512465)

Explicitly fail the negative gidsetsize with EINVAL, as the kernel
does. This means we definitely only call the libc getgroups()
with valid parameters. It also brings the getgroups() code in
to line with the setgroups() code.

Possibly Coverity may still complain about getgroups(0, NULL), but
that would be a false positive.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
---
 linux-user/syscall.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
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Patch

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 94256cc262..f2cb101d83 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -11676,7 +11676,7 @@  static abi_long do_syscall1(CPUArchState *cpu_env, int num, abi_long arg1,
             g_autofree gid_t *grouplist = NULL;
             int i;
 
-            if (gidsetsize > NGROUPS_MAX) {
+            if (gidsetsize > NGROUPS_MAX || gidsetsize < 0) {
                 return -TARGET_EINVAL;
             }
             if (gidsetsize > 0) {
@@ -12012,7 +12012,7 @@  static abi_long do_syscall1(CPUArchState *cpu_env, int num, abi_long arg1,
             g_autofree gid_t *grouplist = NULL;
             int i;
 
-            if (gidsetsize > NGROUPS_MAX) {
+            if (gidsetsize > NGROUPS_MAX || gidsetsize < 0) {
                 return -TARGET_EINVAL;
             }
             if (gidsetsize > 0) {