[GIT PULL] userns bug fix for 4.17-rc3

Eric W. Biederman ebiederm at xmission.com
Tue Apr 24 23:46:40 UTC 2018


Please pull the userns-linus branch from the git tree:

   git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git userns-linus

   HEAD: 1f5781725dcbb026438e77091c91a94f678c3522 commoncap: Handle memory allocation failure

Just a small fix to properly set the return code on error.

From: Tetsuo Handa <penguin-kernel at I-love.SAKURA.ne.jp>
Date: Tue, 10 Apr 2018 15:15:16 +0900
Subject: [PATCH] commoncap: Handle memory allocation failure.

syzbot is reporting NULL pointer dereference at xattr_getsecurity() [1],
for cap_inode_getsecurity() is returning sizeof(struct vfs_cap_data) when
memory allocation failed. Return -ENOMEM if memory allocation failed.

[1] https://syzkaller.appspot.com/bug?id=a55ba438506fe68649a5f50d2d82d56b365e0107

Signed-off-by: Tetsuo Handa <penguin-kernel at I-love.SAKURA.ne.jp>
Fixes: 8db6c34f1dbc8e06 ("Introduce v3 namespaced file capabilities")
Reported-by: syzbot <syzbot+9369930ca44f29e60e2d at syzkaller.appspotmail.com>
Cc: stable <stable at vger.kernel.org> # 4.14+
Acked-by: Serge E. Hallyn <serge at hallyn.com>
Acked-by: James Morris <james.morris at microsoft.com>
Signed-off-by: Eric W. Biederman <ebiederm at xmission.com>
 security/commoncap.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/security/commoncap.c b/security/commoncap.c
index 48620c93d697..1ce701fcb3f3 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -449,6 +449,8 @@ int cap_inode_getsecurity(struct inode *inode, const char *name, void **buffer,
 			memcpy(&cap->data, &nscap->data, sizeof(__le32) * 2 * VFS_CAP_U32);
 			cap->magic_etc = cpu_to_le32(magic);
+		} else {
+			size = -ENOMEM;

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