6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ye Bin yebin10@huawei.com
[ Upstream commit 7375f22495e7cd1c5b3b5af9dcc4f6dffe34ce49 ]
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 the bh is not allocated on the stack, it belongs to a folio. Freeing a buffer head which belongs to a folio is done by drop_buffers() which will fail to free buffers which are still locked. So it is safe to call put_bh() before __end_buffer_read_notouch().
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Ye Bin yebin10@huawei.com Link: https://lore.kernel.org/20250811141830.343774-1-yebin@huaweicloud.com Reviewed-by: Matthew Wilcox (Oracle) willy@infradead.org Signed-off-by: Christian Brauner brauner@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/buffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/buffer.c b/fs/buffer.c index 4b86e971efd8..32df6163ffed 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);