Subject: CVE-2024-42115: jffs2: Fix potential illegal address access in jffs2_free_inode

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

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

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

jffs2: Fix potential illegal address access in jffs2_free_inode

During the stress testing of the jffs2 file system,the following
abnormal printouts were found:
[ 2430.649000] Unable to handle kernel paging request at virtual address 0069696969696948
[ 2430.649622] Mem abort info:
[ 2430.649829]   ESR = 0x96000004
[ 2430.650115]   EC = 0x25: DABT (current EL), IL = 32 bits
[ 2430.650564]   SET = 0, FnV = 0
[ 2430.650795]   EA = 0, S1PTW = 0
[ 2430.651032]   FSC = 0x04: level 0 translation fault
[ 2430.651446] Data abort info:
[ 2430.651683]   ISV = 0, ISS = 0x00000004
[ 2430.652001]   CM = 0, WnR = 0
[ 2430.652558] [0069696969696948] address between user and kernel address ranges
[ 2430.653265] Internal error: Oops: 96000004 [#1] PREEMPT SMP
[ 2430.654512] CPU: 2 PID: 20919 Comm: cat Not tainted 5.15.25-g512f31242bf6 #33
[ 2430.655008] Hardware name: linux,dummy-virt (DT)
[ 2430.655517] pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 2430.656142] pc : kfree+0x78/0x348
[ 2430.656630] lr : jffs2_free_inode+0x24/0x48
[ 2430.657051] sp : ffff800009eebd10
[ 2430.657355] x29: ffff800009eebd10 x28: 0000000000000001 x27: 0000000000000000
[ 2430.658327] x26: ffff000038f09d80 x25: 0080000000000000 x24: ffff800009d38000
[ 2430.658919] x23: 5a5a5a5a5a5a5a5a x22: ffff000038f09d80 x21: ffff8000084f0d14
[ 2430.659434] x20: ffff0000bf9a6ac0 x19: 0169696969696940 x18: 0000000000000000
[ 2430.659969] x17: ffff8000b6506000 x16: ffff800009eec000 x15: 0000000000004000
[ 2430.660637] x14: 0000000000000000 x13: 00000001000820a1 x12: 00000000000d1b19
[ 2430.661345] x11: 0004000800000000 x10: 0000000000000001 x9 : ffff8000084f0d14
[ 2430.662025] x8 : ffff0000bf9a6b40 x7 : ffff0000bf9a6b48 x6 : 0000000003470302
[ 2430.662695] x5 : ffff00002e41dcc0 x4 : ffff0000bf9aa3b0 x3 : 0000000003470342
[ 2430.663486] x2 : 0000000000000000 x1 : ffff8000084f0d14 x0 : fffffc0000000000
[ 2430.664217] Call trace:
[ 2430.664528]  kfree+0x78/0x348
[ 2430.664855]  jffs2_free_inode+0x24/0x48
[ 2430.665233]  i_callback+0x24/0x50
[ 2430.665528]  rcu_do_batch+0x1ac/0x448
[ 2430.665892]  rcu_core+0x28c/0x3c8
[ 2430.666151]  rcu_core_si+0x18/0x28
[ 2430.666473]  __do_softirq+0x138/0x3cc
[ 2430.666781]  irq_exit+0xf0/0x110
[ 2430.667065]  handle_domain_irq+0x6c/0x98
[ 2430.667447]  gic_handle_irq+0xac/0xe8
[ 2430.667739]  call_on_irq_stack+0x28/0x54
The parameter passed to kfree was 5a5a5a5a, which corresponds to the target field of
the jffs_inode_info structure. It was found that all variables in the jffs_inode_info
structure were 5a5a5a5a, except for the first member sem. It is suspected that these
variables are not initialized because they were set to 5a5a5a5a during memory testing,
which is meant to detect uninitialized memory.The sem variable is initialized in the
function jffs2_i_init_once, while other members are initialized in
the function jffs2_init_inode_info.

The function jffs2_init_inode_info is called after iget_locked,
but in the iget_locked function, the destroy_inode process is triggered,
which releases the inode and consequently, the target member of the inode
is not initialized.In concurrent high pressure scenarios, iget_locked
may enter the destroy_inode branch as described in the code.

Since the destroy_inode functionality of jffs2 only releases the target,
the fix method is to set target to NULL in jffs2_i_init_once.

The Linux kernel CVE team has assigned CVE-2024-42115 to this issue.

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

	Fixed in 4.19.318 with commit b6c8b3e31eb8
	Fixed in 5.4.280 with commit 0b3246052e01
	Fixed in 5.10.222 with commit 6d6d94287f63
	Fixed in 5.15.163 with commit 5ca26334fc8a
	Fixed in 6.1.98 with commit 751987a5d8ea
	Fixed in 6.6.39 with commit d0bbbf31462a
	Fixed in 6.9.9 with commit 05fc1ef892f8
	Fixed in 6.10 with commit af9a8730ddb6

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-2024-42115
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:
	fs/jffs2/super.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/b6c8b3e31eb88c85094d848a0bd8b4bafe67e4d8
	https://git.kernel.org/stable/c/0b3246052e01e61a55bb3a15b76acb006759fe67
	https://git.kernel.org/stable/c/6d6d94287f6365282bbf41e9a5b5281985970789
	https://git.kernel.org/stable/c/5ca26334fc8a3711fed14db7f9eb1c621be4df65
	https://git.kernel.org/stable/c/751987a5d8ead0cc405fad96e83ebbaa51c82dbc
	https://git.kernel.org/stable/c/d0bbbf31462a400bef4df33e22de91864f475455
	https://git.kernel.org/stable/c/05fc1ef892f862c1197b11b288bc00f602d2df0c
	https://git.kernel.org/stable/c/af9a8730ddb6a4b2edd779ccc0aceb994d616830