From: Ye Bin <yebin10@xxxxxxxxxx>
There's issue as follows:
BUG: KASAN: stack-out-of-bounds in end_buffer_read_sync+0xe3/0x110
Read of size 8 at addr ffffc9000168f7f8 by task swapper/3/0
CPU: 3 UID: 0 PID: 0 Comm: swapper/3 Not tainted 6.16.0-862.14.0.6.x86_64
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
Call Trace:
<IRQ>
dump_stack_lvl+0x55/0x70
print_address_description.constprop.0+0x2c/0x390
print_report+0xb4/0x270
kasan_report+0xb8/0xf0
end_buffer_read_sync+0xe3/0x110
end_bio_bh_io_sync+0x56/0x80
blk_update_request+0x30a/0x720
scsi_end_request+0x51/0x2b0
scsi_io_completion+0xe3/0x480
? scsi_device_unbusy+0x11e/0x160
blk_complete_reqs+0x7b/0x90
handle_softirqs+0xef/0x370
irq_exit_rcu+0xa5/0xd0
sysvec_apic_timer_interrupt+0x6e/0x90
</IRQ>
Above issue happens when do ntfs3 filesystem mount, issue may happens
as follows:
mount IRQ
ntfs_fill_super
read_cache_page
do_read_cache_folio
filemap_read_folio
mpage_read_folio
do_mpage_readpage
ntfs_get_block_vbo
bh_read
submit_bh
wait_on_buffer(bh);
blk_complete_reqs
scsi_io_completion
scsi_end_request
blk_update_request
end_bio_bh_io_sync
end_buffer_read_sync
__end_buffer_read_notouch
unlock_buffer
wait_on_buffer(bh);--> return will return to caller
put_bh
--> trigger stack-out-of-bounds
In the mpage_read_folio() function, the stack variable 'map_bh' is
passed to ntfs_get_block_vbo(). Once unlock_buffer() unlocks and
wait_on_buffer() returns to continue processing, the stack variable
is likely to be reclaimed. Consequently, during the end_buffer_read_sync()
process, calling put_bh() may result in stack overrun.
If it is not a stack variable, since the reference count of the
buffer_head is released after unlocking, it cannot be released during
drop_buffers. This poses a risk of buffer_head leakage.
To solve above issue first call put_bh() before unlock_buffer. This
should be safe because during the release, discard_buffer() will call
lock_buffer().
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Ye Bin <yebin10@xxxxxxxxxx>
---
fs/buffer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/buffer.c b/fs/buffer.c
index ead4dc85debd..6a8752f7bbed 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -157,8 +157,8 @@ static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate)
*/
void end_buffer_read_sync(struct buffer_head *bh, int uptodate)
{
- __end_buffer_read_notouch(bh, uptodate);
put_bh(bh);
+ __end_buffer_read_notouch(bh, uptodate);
}
EXPORT_SYMBOL(end_buffer_read_sync);
--
2.34.1
