| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.4 025/453] afs: Fix memory leak when mounting with multiple source parameters | Date | Mon, 28 Dec 2020 13:44:21 +0100 |
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From: David Howells <dhowells@redhat.com>
[ Upstream commit 4cb682964706deffb4861f0a91329ab3a705039f ]
There's a memory leak in afs_parse_source() whereby multiple source= parameters overwrite fc->source in the fs_context struct without freeing the previously recorded source.
Fix this by only permitting a single source parameter and rejecting with an error all subsequent ones.
This was caught by syzbot with the kernel memory leak detector, showing something like the following trace:
unreferenced object 0xffff888114375440 (size 32): comm "repro", pid 5168, jiffies 4294923723 (age 569.948s) backtrace: slab_post_alloc_hook+0x42/0x79 __kmalloc_track_caller+0x125/0x16a kmemdup_nul+0x24/0x3c vfs_parse_fs_string+0x5a/0xa1 generic_parse_monolithic+0x9d/0xc5 do_new_mount+0x10d/0x15a do_mount+0x5f/0x8e __do_sys_mount+0xff/0x127 do_syscall_64+0x2d/0x3a entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fixes: 13fcc6837049 ("afs: Add fs_context support") Reported-by: syzbot+86dc6632faaca40133ab@syzkaller.appspotmail.com Signed-off-by: David Howells <dhowells@redhat.com> cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> --- fs/afs/super.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/fs/afs/super.c b/fs/afs/super.c index 7f8a9b3137bff..eb04dcc543289 100644 --- a/fs/afs/super.c +++ b/fs/afs/super.c @@ -236,6 +236,9 @@ static int afs_parse_source(struct fs_context *fc, struct fs_parameter *param) _enter(",%s", name); + if (fc->source) + return invalf(fc, "kAFS: Multiple sources not supported"); + if (!name) { printk(KERN_ERR "kAFS: no volume name specified\n"); return -EINVAL; -- 2.27.0
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