linux-cve-announce - CVE-2025-38229: media: cxusb: no longer judge rbuf when the write fails

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Message-ID: <2025070428-CVE-2025-38229-d2d5@gregkh>
Date: Fri,  4 Jul 2025 15:37:58 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38229: media: cxusb: no longer judge rbuf when the write fails

From: Greg Kroah-Hartman <gregkh@...nel.org>

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

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

media: cxusb: no longer judge rbuf when the write fails

syzbot reported a uninit-value in cxusb_i2c_xfer. [1]

Only when the write operation of usb_bulk_msg() in dvb_usb_generic_rw()
succeeds and rlen is greater than 0, the read operation of usb_bulk_msg()
will be executed to read rlen bytes of data from the dvb device into the
rbuf.

In this case, although rlen is 1, the write operation failed which resulted
in the dvb read operation not being executed, and ultimately variable i was
not initialized.

[1]
BUG: KMSAN: uninit-value in cxusb_gpio_tuner drivers/media/usb/dvb-usb/cxusb.c:124 [inline]
BUG: KMSAN: uninit-value in cxusb_i2c_xfer+0x153a/0x1a60 drivers/media/usb/dvb-usb/cxusb.c:196
 cxusb_gpio_tuner drivers/media/usb/dvb-usb/cxusb.c:124 [inline]
 cxusb_i2c_xfer+0x153a/0x1a60 drivers/media/usb/dvb-usb/cxusb.c:196
 __i2c_transfer+0xe25/0x3150 drivers/i2c/i2c-core-base.c:-1
 i2c_transfer+0x317/0x4a0 drivers/i2c/i2c-core-base.c:2315
 i2c_transfer_buffer_flags+0x125/0x1e0 drivers/i2c/i2c-core-base.c:2343
 i2c_master_send include/linux/i2c.h:109 [inline]
 i2cdev_write+0x210/0x280 drivers/i2c/i2c-dev.c:183
 do_loop_readv_writev fs/read_write.c:848 [inline]
 vfs_writev+0x963/0x14e0 fs/read_write.c:1057
 do_writev+0x247/0x5c0 fs/read_write.c:1101
 __do_sys_writev fs/read_write.c:1169 [inline]
 __se_sys_writev fs/read_write.c:1166 [inline]
 __x64_sys_writev+0x98/0xe0 fs/read_write.c:1166
 x64_sys_call+0x2229/0x3c80 arch/x86/include/generated/asm/syscalls_64.h:21
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x1e0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The Linux kernel CVE team has assigned CVE-2025-38229 to this issue.


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

	Issue introduced in 2.6.13 with commit 22c6d93a73105fddd58796d7cb10f5f90ee2a338 and fixed in 5.10.239 with commit 390b864e3281802109dfe56e508396683e125653
	Issue introduced in 2.6.13 with commit 22c6d93a73105fddd58796d7cb10f5f90ee2a338 and fixed in 5.15.186 with commit 41807a5f67420464ac8ee7741504f6b5decb3b7c
	Issue introduced in 2.6.13 with commit 22c6d93a73105fddd58796d7cb10f5f90ee2a338 and fixed in 6.1.142 with commit 84eca597baa346f09b30accdaeca10ced3eeba2d
	Issue introduced in 2.6.13 with commit 22c6d93a73105fddd58796d7cb10f5f90ee2a338 and fixed in 6.6.95 with commit 04354c529c8246a38ae28f713fd6bfdc028113bc
	Issue introduced in 2.6.13 with commit 22c6d93a73105fddd58796d7cb10f5f90ee2a338 and fixed in 6.12.35 with commit 9bff888c92f5c25effbb876d22a793c2388c1ccc
	Issue introduced in 2.6.13 with commit 22c6d93a73105fddd58796d7cb10f5f90ee2a338 and fixed in 6.15.4 with commit 8b35b50b7e98d8e9a0a27257c8424448afae10de
	Issue introduced in 2.6.13 with commit 22c6d93a73105fddd58796d7cb10f5f90ee2a338 and fixed in 6.16-rc1 with commit 73fb3b92da84637e3817580fa205d48065924e15

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-2025-38229
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/media/usb/dvb-usb/cxusb.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/390b864e3281802109dfe56e508396683e125653
	https://git.kernel.org/stable/c/41807a5f67420464ac8ee7741504f6b5decb3b7c
	https://git.kernel.org/stable/c/84eca597baa346f09b30accdaeca10ced3eeba2d
	https://git.kernel.org/stable/c/04354c529c8246a38ae28f713fd6bfdc028113bc
	https://git.kernel.org/stable/c/9bff888c92f5c25effbb876d22a793c2388c1ccc
	https://git.kernel.org/stable/c/8b35b50b7e98d8e9a0a27257c8424448afae10de
	https://git.kernel.org/stable/c/73fb3b92da84637e3817580fa205d48065924e15