Subject: CVE-2024-46715: driver: iio: add missing checks on iio_info's callback access

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

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

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

driver: iio: add missing checks on iio_info's callback access

Some callbacks from iio_info structure are accessed without any check, so
if a driver doesn't implement them trying to access the corresponding
sysfs entries produce a kernel oops such as:

[ 2203.527791] Unable to handle kernel NULL pointer dereference at virtual address 00000000 when execute
[...]
[ 2203.783416] Call trace:
[ 2203.783429]  iio_read_channel_info_avail from dev_attr_show+0x18/0x48
[ 2203.789807]  dev_attr_show from sysfs_kf_seq_show+0x90/0x120
[ 2203.794181]  sysfs_kf_seq_show from seq_read_iter+0xd0/0x4e4
[ 2203.798555]  seq_read_iter from vfs_read+0x238/0x2a0
[ 2203.802236]  vfs_read from ksys_read+0xa4/0xd4
[ 2203.805385]  ksys_read from ret_fast_syscall+0x0/0x54
[ 2203.809135] Exception stack(0xe0badfa8 to 0xe0badff0)
[ 2203.812880] dfa0:                   00000003 b6f10f80 00000003 b6eab000 00020000 00000000
[ 2203.819746] dfc0: 00000003 b6f10f80 7ff00000 00000003 00000003 00000000 00020000 00000000
[ 2203.826619] dfe0: b6e1bc88 bed80958 b6e1bc94 b6e1bcb0
[ 2203.830363] Code: bad PC value
[ 2203.832695] ---[ end trace 0000000000000000 ]---

The Linux kernel CVE team has assigned CVE-2024-46715 to this issue.

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

	Fixed in 6.1.109 with commit 0cc7e0ee31e5
	Fixed in 6.6.50 with commit 72f022ebb9de
	Fixed in 6.10.9 with commit dc537a72f648
	Fixed in 6.11 with commit c4ec8dedca96

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-2024-46715
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/iio/industrialio-core.c
	drivers/iio/industrialio-event.c
	drivers/iio/inkern.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/0cc7e0ee31e5c44904e98e2229d591e093282a70
	https://git.kernel.org/stable/c/72f022ebb9deac28663fa4c04ba315ed5d6654d1
	https://git.kernel.org/stable/c/dc537a72f64890d883d24ae4ac58733fc5bc523d
	https://git.kernel.org/stable/c/c4ec8dedca961db056ec85cb7ca8c9f7e2e92252