Re: divide error in alauda_transport

[Alan Stern]

On Sun, Mar 17, 2024 at 04:31:01PM +0800, xingwei lee wrote:
> Hello I found a bug in latest upstream titled "divide error in
> alauda_transport", and maybe is realted with usb.
> I comfired in the latest upstream the poc tree can trigger the issue.
> 
> If you fix this issue, please add the following tag to the commit:
> Reported-by: xingwei lee <xrivendell7@xxxxxxxxx>
> Reported-by: yue sun <samsun1006219@xxxxxxxxx>
> 
> kernel: upstream 9187210eee7d87eea37b45ea93454a88681894a4
> config: https://syzkaller.appspot.com/text?tag=KernelConfig&x=1c6662240382da2
> with KASAN enabled
> compiler: gcc (Debian 12.2.0-14) 12.2.0
> 
> divide error: 0000 [#1] PREEMPT SMP KASAN NOPTI
> CPU: 2 PID: 8229 Comm: usb-storage Not tainted 6.8.0-05202-g9187210eee7d #20
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> 1.16.2-1.fc38 04/01/2014
> RIP: 0010:alauda_read_data drivers/usb/storage/alauda.c:954 [inline]
> RIP: 0010:alauda_transport+0xcaf/0x3830 drivers/usb/storage/alauda.c:1184

Can you please test the patch below?

Alan Stern



Index: usb-devel/drivers/usb/storage/alauda.c
===================================================================
--- usb-devel.orig/drivers/usb/storage/alauda.c
+++ usb-devel/drivers/usb/storage/alauda.c
@@ -951,7 +951,6 @@ static int alauda_read_data(struct us_da
 		unsigned int lba_offset = lba - (zone * uzonesize);
 		unsigned int pages;
 		u16 pba;
-		alauda_ensure_map_for_zone(us, zone);
 
 		/* Not overflowing capacity? */
 		if (lba >= max_lba) {
@@ -961,6 +960,8 @@ static int alauda_read_data(struct us_da
 			break;
 		}
 
+		alauda_ensure_map_for_zone(us, zone);
+
 		/* Find number of pages we can read in this block */
 		pages = min(sectors, blocksize - page);
 		len = pages << pageshift;