On Mon, Feb 26, 2024 at 11:59:06AM +0100, Oliver Neukum wrote: > Hi, > > On 26.02.24 10:42, syzbot wrote: > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: f2e367d6ad3b Merge tag 'for-6.8/dm-fix-3' of git://git.ker.. > > git tree: upstream > > console+strace: https://syzkaller.appspot.com/x/log.txt?x=114e10e4180000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=eff9f3183d0a20dd > > dashboard link: https://syzkaller.appspot.com/bug?extid=28748250ab47a8f04100 > > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1064b372180000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10aca6ac180000 > > > > Downloadable assets: > > disk image: https://storage.googleapis.com/syzbot-assets/c55ca1fdc5ad/disk-f2e367d6.raw.xz > > vmlinux: https://storage.googleapis.com/syzbot-assets/4556a82fb4ed/vmlinux-f2e367d6.xz > > kernel image: https://storage.googleapis.com/syzbot-assets/95338ed9dad1/bzImage-f2e367d6.xz > > > > The issue was bisected to: > > > > commit 321da3dc1f3c92a12e3c5da934090d2992a8814c > > Author: Martin K. Petersen <martin.petersen@xxxxxxxxxx> > > Date: Tue Feb 13 14:33:06 2024 +0000 > > > > scsi: sd: usb_storage: uas: Access media prior to querying device properties > > preliminary analysis: > > It oopses here: > > } else { > if (!id[ATA_ID_SECTORS] || !id[ATA_ID_HEADS]) > goto too_early; Those two lines are debugging code you added, right? > sectnum = (u8)((lba % id[ATA_ID_SECTORS]) + 1); > cylinder = (u16)(lba / (id[ATA_ID_SECTORS] * > id[ATA_ID_HEADS])); > > in isd200_scsi_to_ata() because it must not be called before isd200_get_inquiry_data() > has completed. It can't be; isd200_get_inquiry_data is called by isd200_Initialization during probe before any SCSI commands are transmitted. > That raises two questions. > > 1) should we limit the read_before_ms flag to the cases transparent SCSI is used? That won't help; the inquiry data will still be wrong. > 2) does isd200_get_inquiry_data() need to validate what it reads? Yes. At least to make sure that we're not going to divide by 0. This means that id[ATA_ID_SECTORS] and id[ATA_ID_HEADS] must both be > 0. Since they are 16-bit quantities, we don't have to worry about them overflowing. Do you want to submit a fix for syzbot to test? Alan Stern
