Subject: CVE-2021-47015: bnxt_en: Fix RX consumer index logic in the error path.

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

bnxt_en: Fix RX consumer index logic in the error path.

In bnxt_rx_pkt(), the RX buffers are expected to complete in order.
If the RX consumer index indicates an out of order buffer completion,
it means we are hitting a hardware bug and the driver will abort all
remaining RX packets and reset the RX ring.  The RX consumer index
that we pass to bnxt_discard_rx() is not correct.  We should be
passing the current index (tmp_raw_cons) instead of the old index
(raw_cons).  This bug can cause us to be at the wrong index when
trying to abort the next RX packet.  It can crash like this:

 #0 [ffff9bbcdf5c39a8] machine_kexec at ffffffff9b05e007
 #1 [ffff9bbcdf5c3a00] __crash_kexec at ffffffff9b111232
 #2 [ffff9bbcdf5c3ad0] panic at ffffffff9b07d61e
 #3 [ffff9bbcdf5c3b50] oops_end at ffffffff9b030978
 #4 [ffff9bbcdf5c3b78] no_context at ffffffff9b06aaf0
 #5 [ffff9bbcdf5c3bd8] __bad_area_nosemaphore at ffffffff9b06ae2e
 #6 [ffff9bbcdf5c3c28] bad_area_nosemaphore at ffffffff9b06af24
 #7 [ffff9bbcdf5c3c38] __do_page_fault at ffffffff9b06b67e
 #8 [ffff9bbcdf5c3cb0] do_page_fault at ffffffff9b06bb12
 #9 [ffff9bbcdf5c3ce0] page_fault at ffffffff9bc015c5
    [exception RIP: bnxt_rx_pkt+237]
    RIP: ffffffffc0259cdd  RSP: ffff9bbcdf5c3d98  RFLAGS: 00010213
    RAX: 000000005dd8097f  RBX: ffff9ba4cb11b7e0  RCX: ffffa923cf6e9000
    RDX: 0000000000000fff  RSI: 0000000000000627  RDI: 0000000000001000
    RBP: ffff9bbcdf5c3e60   R8: 0000000000420003   R9: 000000000000020d
    R10: ffffa923cf6ec138  R11: ffff9bbcdf5c3e83  R12: ffff9ba4d6f928c0
    R13: ffff9ba4cac28080  R14: ffff9ba4cb11b7f0  R15: ffff9ba4d5a30000
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018

The Linux kernel CVE team has assigned CVE-2021-47015 to this issue.

Affected and fixed versions
===========================

	Issue introduced in 5.1 with commit a1b0e4e684e9 and fixed in 5.4.119 with commit b1523e4ba293
	Issue introduced in 5.1 with commit a1b0e4e684e9 and fixed in 5.10.37 with commit 4fcaad2b7dac
	Issue introduced in 5.1 with commit a1b0e4e684e9 and fixed in 5.11.21 with commit e187ef83c04a
	Issue introduced in 5.1 with commit a1b0e4e684e9 and fixed in 5.12.4 with commit 3fbc5bc651d6
	Issue introduced in 5.1 with commit a1b0e4e684e9 and fixed in 5.13 with commit bbd6f0a94813
	Issue introduced in 4.9.169 with commit 8e302e8e10b0
	Issue introduced in 4.14.112 with commit 46281ee85b65
	Issue introduced in 4.19.35 with commit d2d055a55403
	Issue introduced in 5.0.8 with commit aecbbae850ed

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2021-47015
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	drivers/net/ethernet/broadcom/bnxt/bnxt.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/b1523e4ba293b2a32d9fabaf70c1dcaa6e3e2847
	https://git.kernel.org/stable/c/4fcaad2b7dac3f16704f8118c7e481024ddbd3ed
	https://git.kernel.org/stable/c/e187ef83c04a5d23e68d39cfdff1a1931e29890c
	https://git.kernel.org/stable/c/3fbc5bc651d688fbea2a59cdc91520a2f5334d0a
	https://git.kernel.org/stable/c/bbd6f0a948139970f4a615dff189d9a503681a39