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)
hex dump (first 32 bytes):
25 5e 5d 24 5b 2b 25 5d 28 24 7b 3a 0f 6b 5b 29 %^]$[+%](${:.k[)
2d 3a 00 00 00 00 00 00 00 00 00 00 00 00 00 00 -:..............
backtrace:
[<0000000072e41e46>] slab_post_alloc_hook+0x42/0x79
[<00000000d8b306e6>] __kmalloc_track_caller+0x125/0x16a
[<0000000028ae1813>] kmemdup_nul+0x24/0x3c
[<0000000072927516>] vfs_parse_fs_string+0x5a/0xa1
[<0000000045b4b196>] generic_parse_monolithic+0x9d/0xc5
[<0000000084462c80>] do_new_mount+0x10d/0x15a
[<000000008aef98c5>] do_mount+0x5f/0x8e
[<000000002998d632>] __do_sys_mount+0xff/0x127
[<00000000faf86d94>] do_syscall_64+0x2d/0x3a
[<000000004495c173>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fixes: 13fcc6837049 ("afs: Add fs_context support")
Reported-by: [email protected]
Signed-off-by: David Howells <[email protected]>
cc: Randy Dunlap <[email protected]>
---
fs/afs/super.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/fs/afs/super.c b/fs/afs/super.c
index 6c5900df6aa5..e38bb1e7a4d2 100644
--- a/fs/afs/super.c
+++ b/fs/afs/super.c
@@ -230,6 +230,9 @@ 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;
