Messages in this thread | | | From | Arnd Bergmann <> | Date | Thu, 11 Mar 2021 14:30:01 +0100 | Subject | Re: arm64 syzbot instances |
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On Thu, Mar 11, 2021 at 12:38 PM Dmitry Vyukov <dvyukov@google.com> wrote: > > The instances found few arm64-specific issues that we have not > observed on other instances:
I've had a brief look at these:
> https://syzkaller.appspot.com/bug?id=1d22a2cc3521d5cf6b41bd6b825793c2015f861f
This one doesn't seem arm64 specific at all. While the KASAN report has shown up on arm64, the link to https://syzkaller.appspot.com/bug?id=aa8808729c0a3540e6a29f0d45394665caf79dca seems to be for x86 machines running into the same problem.
Looking deeper into the log, I see that fw_load_sysfs_fallback() finds an existing list entry on the global "pending_fw_head" list, which seems to have been freed earlier (the allocation listed here is not for a firmware load, so presumably it was recycled in the meantime). The log shows that this is the second time that loading the regulatory database failed in that run, so my guess is that it was the first failed load that left the freed firmware private data on the list, but I don't see how that happened.
> https://syzkaller.appspot.com/bug?id=bb2c16b0e13b4de4bbf22cf6a4b9b16fb0c20eea
This one rings a bell: opening a 8250 uart on a well-known port must fail when no I/O ports are registered in the system, or when the PCI I/O ports are mapped to an invalid area.
It seems to be attempting a register access at I/O port '1' (virtual address 0xfffffbfffe800001 is one byte into the well-known PCI_IOBASE), which is an unusual place for a UART, traditional PCs had it at 0x3F8.
This could be either a result of qemu claiming to support a PIO based UART at the first available address, or the table of UARTS being uninitialized .bss memory.
Definitely an arm64 specific bug.
> https://syzkaller.appspot.com/bug?id=b75386f45318ec181b7f49260d619fac9877d456
A freed entry on the timer list caused a bug when adding another entry.
The allocation from alloc_fdtable does not seem to be the one at fault, as the fdtable does not contain a timer. Several of the linked kasan reports point to ext4_fill_super() as the code that allocated and freed the timer list entry, so it's possible that this is the same timer that later fails to be inserted if we ever get to kfree(sbi) without killing the timer first.
I don't see how that could happen, but the code was recently rewritten in c92dc856848f ("ext4: defer saving error info from atomic context")
> https://syzkaller.appspot.com/bug?id=5a1bc29bca656159f95c7c8bb30e3776ca860332
I see that reiserfs_xattr_jcreate_nblocks() is dereferencing a NULL inode pointer -- inode->i_sb has offset 0x30. However, that doesn't make any sense with the call chain, as the pointer was newly allocated and checked for NULL.
Arnd
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