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When scanning namespaces, it is possible to get valid data from the first
call to nvme_identify_ns() in nvme_alloc_ns(), but not from the second
call in nvme_update_ns_info_block(). In particular, if the NSID becomes
inactive between the two commands, a storage device may return a buffer
filled with zero as per 4.1.5.1. In this case, we can get a kernel crash
due to a divide-by-zero in blk_stack_limits() because ns->lba_shift will
be set to zero.
PID: 326 TASK: ffff95fec3cd8000 CPU: 29 COMMAND: "kworker/u98:10"
#0 [ffffad8f8702f9e0] machine_kexec at ffffffff91c76ec7
#1 [ffffad8f8702fa38] __crash_kexec at ffffffff91dea4fa
#2 [ffffad8f8702faf8] crash_kexec at ffffffff91deb788
#3 [ffffad8f8702fb00] oops_end at ffffffff91c2e4bb
#4 [ffffad8f8702fb20] do_trap at ffffffff91c2a4ce
#5 [ffffad8f8702fb70] do_error_trap at ffffffff91c2a595
#6 [ffffad8f8702fbb0] exc_divide_error at ffffffff928506e6
#7 [ffffad8f8702fbd0] asm_exc_divide_error at ffffffff92a00926
[exception RIP: blk_stack_limits+434]
RIP: ffffffff92191872 RSP: ffffad8f8702fc80 RFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff95efa0c91800 RCX: 0000000000000001
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000001
RBP: 00000000ffffffff R8: ffff95fec7df35a8 R9: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffff95fed33c09a8
ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018
#8 [ffffad8f8702fce0] nvme_update_ns_info_block at ffffffffc06d3533 [nvme_core]
#9 [ffffad8f8702fd18] nvme_scan_ns at ffffffffc06d6fa7 [nvme_core]
This happened when the check for valid data was moved out of nvme_identify_ns()
into one of the callers. Fix this by checking in both callers.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=218186
Fixes: 0dd6fff2aa ("nvme: bring back auto-removal of deleted namespaces during sequential scan")
Cc: stable@vger.kernel.org
Signed-off-by: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.