Subject: CVE-2024-49933: blk_iocost: fix more out of bound shifts

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

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

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

blk_iocost: fix more out of bound shifts

Recently running UBSAN caught few out of bound shifts in the
ioc_forgive_debts() function:

UBSAN: shift-out-of-bounds in block/blk-iocost.c:2142:38
shift exponent 80 is too large for 64-bit type 'u64' (aka 'unsigned long
long')
...
UBSAN: shift-out-of-bounds in block/blk-iocost.c:2144:30
shift exponent 80 is too large for 64-bit type 'u64' (aka 'unsigned long
long')
...
Call Trace:
<IRQ>
dump_stack_lvl+0xca/0x130
__ubsan_handle_shift_out_of_bounds+0x22c/0x280
? __lock_acquire+0x6441/0x7c10
ioc_timer_fn+0x6cec/0x7750
? blk_iocost_init+0x720/0x720
? call_timer_fn+0x5d/0x470
call_timer_fn+0xfa/0x470
? blk_iocost_init+0x720/0x720
__run_timer_base+0x519/0x700
...

Actual impact of this issue was not identified but I propose to fix the
undefined behaviour.
The proposed fix to prevent those out of bound shifts consist of
precalculating exponent before using it the shift operations by taking
min value from the actual exponent and maximum possible number of bits.

The Linux kernel CVE team has assigned CVE-2024-49933 to this issue.

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

	Fixed in 5.10.227 with commit 1f61d509257d
	Fixed in 5.15.168 with commit f4ef9bef023d
	Fixed in 6.1.113 with commit 59121bb38fdc
	Fixed in 6.6.55 with commit 1ab2cfe19700
	Fixed in 6.10.14 with commit 1b120f151871
	Fixed in 6.11.3 with commit 364022095bdd
	Fixed in 6.12-rc1 with commit 9bce8005ec0d

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-2024-49933
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:
	block/blk-iocost.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/1f61d509257d6a05763d05bf37943b35306522b1
	https://git.kernel.org/stable/c/f4ef9bef023d5c543cb0f3194ecacfd47ef590ec
	https://git.kernel.org/stable/c/59121bb38fdc01434ea3fe361ee02b59f036227f
	https://git.kernel.org/stable/c/1ab2cfe19700fb3dde4c7dfec392acff34db3120
	https://git.kernel.org/stable/c/1b120f151871eb47ce9f283c007af3f8ae1d990e
	https://git.kernel.org/stable/c/364022095bdd4108efdaaa68576afa4712a5d085
	https://git.kernel.org/stable/c/9bce8005ec0dcb23a58300e8522fe4a31da606fa