linux-kernel - [PATCH v2] pipe: Fix memory leaks in create_pipe

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Message-Id: <20201001025255.29560-1-cai@redhat.com>
Date:   Wed, 30 Sep 2020 22:52:55 -0400
From:   Qian Cai <cai@...hat.com>
To:     David Howells <dhowells@...hat.com>,
        Alexander Viro <viro@...iv.linux.org.uk>
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2] pipe: Fix memory leaks in create_pipe_files()

Calling pipe2() with O_NOTIFICATION_PIPE could results in memory leaks
in an error path or CONFIG_WATCH_QUEUE=n. Plug them.

unreferenced object 0xc00000141114a0d8 (size 992):
  comm "trinity-c61", pid 1353192, jiffies 4296255779 (age 25989.560s)
  hex dump (first 32 bytes):
    80 11 00 00 e8 03 00 00 00 00 00 00 00 00 00 00  ................
    ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff  ................
  backtrace:
    [<00000000abff13d7>] kmem_cache_alloc+0x1b4/0x470
    [<000000009502e5d5>] alloc_inode+0xd0/0x130
    [<00000000ca1c1a21>] new_inode_pseudo+0x1c/0x80
new_inode_pseudo at fs/inode.c:932
    [<000000000c01d1d6>] create_pipe_files+0x48/0x2d0
get_pipe_inode at fs/pipe.c:874
(inlined by) create_pipe_files at fs/pipe.c:914
    [<00000000d13ff4c4>] __do_pipe_flags+0x50/0x120
__do_pipe_flags at fs/pipe.c:965
    [<0000000003941e42>] do_pipe2+0x3c/0x100
do_pipe2 at fs/pipe.c:1013
    [<00000000a006b818>] sys_pipe2+0x1c/0x30
__se_sys_pipe2 at fs/pipe.c:1028
    [<00000000a6925b55>] system_call_exception+0xf8/0x1d0
    [<000000001c6b0740>] system_call_common+0xe8/0x218
unreferenced object 0xc000001f575ce600 (size 512):
  comm "trinity-c61", pid 1353192, jiffies 4296255779 (age 25989.560s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 ad 4e ad de  .............N..
    ff ff ff ff 00 00 00 00 ff ff ff ff ff ff ff ff  ................
  backtrace:
    [<00000000d74d5e3a>] kmem_cache_alloc_trace+0x1c4/0x2d0
    [<0000000061cbc9cb>] alloc_pipe_info+0x88/0x2c0
kmalloc at include/linux/slab.h:554
(inlined by) kzalloc at include/linux/slab.h:666
(inlined by) alloc_pipe_info at fs/pipe.c:793
    [<00000000efd6129c>] create_pipe_files+0x6c/0x2d0
get_pipe_inode at fs/pipe.c:883
(inlined by) create_pipe_files at fs/pipe.c:914
    [<00000000d13ff4c4>] __do_pipe_flags+0x50/0x120
    [<0000000003941e42>] do_pipe2+0x3c/0x100
    [<00000000a006b818>] sys_pipe2+0x1c/0x30
    [<00000000a6925b55>] system_call_exception+0xf8/0x1d0
    [<000000001c6b0740>] system_call_common+0xe8/0x218
unreferenced object 0xc000000d94f20400 (size 1024):
  comm "trinity-c61", pid 1353192, jiffies 4296255779 (age 25989.560s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<00000000e60ee00f>] __kmalloc+0x1e4/0x330
    [<00000000130e8cc8>] alloc_pipe_info+0x154/0x2c0
kmalloc_array at include/linux/slab.h:594
(inlined by) kcalloc at include/linux/slab.h:605
(inlined by) alloc_pipe_info at fs/pipe.c:810
    [<00000000efd6129c>] create_pipe_files+0x6c/0x2d0
    [<00000000d13ff4c4>] __do_pipe_flags+0x50/0x120
    [<0000000003941e42>] do_pipe2+0x3c/0x100
    [<00000000a006b818>] sys_pipe2+0x1c/0x30
    [<00000000a6925b55>] system_call_exception+0xf8/0x1d0
    [<000000001c6b0740>] system_call_common+0xe8/0x218

Fixes: c73be61cede5 ("pipe: Add general notification queue support")
Signed-off-by: Qian Cai <cai@...hat.com>
---
 fs/pipe.c                   | 11 +++++------
 include/linux/watch_queue.h |  4 ++++
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/fs/pipe.c b/fs/pipe.c
index 60dbee457143..6fbfbb8f32e1 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -913,19 +913,18 @@ int create_pipe_files(struct file **res, int flags)
 {
 	struct inode *inode = get_pipe_inode();
 	struct file *f;
+	int ret;
 
 	if (!inode)
 		return -ENFILE;
 
 	if (flags & O_NOTIFICATION_PIPE) {
-#ifdef CONFIG_WATCH_QUEUE
-		if (watch_queue_init(inode->i_pipe) < 0) {
+		ret = watch_queue_init(inode->i_pipe);
+		if (ret < 0) {
+			free_pipe_info(inode->i_pipe);
 			iput(inode);
-			return -ENOMEM;
+			return ret;
 		}
-#else
-		return -ENOPKG;
-#endif
 	}
 
 	f = alloc_file_pseudo(inode, pipe_mnt, "",
diff --git a/include/linux/watch_queue.h b/include/linux/watch_queue.h
index 5e08db2adc31..20665fbe0552 100644
--- a/include/linux/watch_queue.h
+++ b/include/linux/watch_queue.h
@@ -123,5 +123,9 @@ static inline void remove_watch_list(struct watch_list *wlist, u64 id)
 #define watch_sizeof(STRUCT) (sizeof(STRUCT) << WATCH_INFO_LENGTH__SHIFT)
 
 #endif
+static inline int watch_queue_init(struct pipe_inode_info *pipe)
+{
+	return -ENOPKG;
+}
 
 #endif /* _LINUX_WATCH_QUEUE_H */
-- 
2.28.0