On Thu, Jun 20, 2019 at 06:44:28PM +0200, Greg KH wrote:

On Thu, Jun 20, 2019 at 09:30:49AM -0700, Zubin Mithra wrote:

...

Hello,

Syzkaller has triggered a kernel WARNING when fuzzing a 4.14 kernel with the following stacktrace. Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x114/0x1cf lib/dump_stack.c:53 panic+0x1bb/0x3a0 kernel/panic.c:181 __warn.cold.9+0x149/0x186 kernel/panic.c:542 report_bug+0x1f7/0x272 lib/bug.c:186 fixup_bug arch/x86/kernel/traps.c:177 [inline] do_error_trap+0x1c1/0x430 arch/x86/kernel/traps.c:295 do_invalid_op+0x20/0x30 arch/x86/kernel/traps.c:314 invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:944 __remove_privs fs/inode.c:1805 [inline] file_remove_privs+0x291/0x4c0 fs/inode.c:1827 __generic_file_write_iter+0x166/0x5b0 mm/filemap.c:3096 blkdev_write_iter+0x1f5/0x3b0 fs/block_dev.c:1905 call_write_iter include/linux/fs.h:1782 [inline] new_sync_write fs/read_write.c:471 [inline] __vfs_write+0x53f/0x7d0 fs/read_write.c:484 vfs_write+0x18c/0x500 fs/read_write.c:546 SYSC_write fs/read_write.c:593 [inline] SyS_write+0xf4/0x230 fs/read_write.c:585 do_syscall_32_irqs_on arch/x86/entry/common.c:340 [inline] do_fast_syscall_32+0x3c1/0xbf1 arch/x86/entry/common.c:403 entry_SYSENTER_compat+0x84/0x96 arch/x86/entry/entry_64_compat.S:139

Could the following patch be applied to 5.0.y, 4.19.y, 4.14.y? The commit is present in 5.1.y.

• f69e749a4935 ("Abort file_remove_privs() for non-reg. files")

5.0 is long end-of-life, but 4.19.y and 4.14.y is good. What about older kernels? it seems to be applicable there too, right?

Yes, 4.9.y and 4.4.y as well.

Thanks, - Zubin

thanks,

greg k-h