We've seen cases where people passed negative numbers to
posix_acl_alloc() and we fixed the caller.  For example 093019cf1b "xfs:
fix acl count validation in xfs_acl_from_disk()".  But there are other
places which might be affected like ext4_acl_from_disk() which checks
for negative but doesn't check an upper limit.

Signed-off-by: Dan Carpenter <dan.carpen...@oracle.com>

diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index cea4623..cd7fd2f 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -46,7 +46,12 @@ posix_acl_alloc(int count, gfp_t flags)
 {
        const size_t size = sizeof(struct posix_acl) +
                            count * sizeof(struct posix_acl_entry);
-       struct posix_acl *acl = kmalloc(size, flags);
+       struct posix_acl *acl;
+
+       if (count < 0 || count > (SIZE_MAX - sizeof(struct posix_acl) /
+                                       sizeof(struct posix_acl_entry)))
+               return NULL;
+       acl = kmalloc(size, flags);
        if (acl)
                posix_acl_init(acl, count);
        return acl;
--
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