CVE-2024-26613: net/rds: Fix UBSAN: array-index-out-of-bounds in rds_cmsg_recv

[Lee Jones <lee@kernel.org>]

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

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

net/rds: Fix UBSAN: array-index-out-of-bounds in rds_cmsg_recv

Syzcaller UBSAN crash occurs in rds_cmsg_recv(),
which reads inc->i_rx_lat_trace[j + 1] with index 4 (3 + 1),
but with array size of 4 (RDS_RX_MAX_TRACES).
Here 'j' is assigned from rs->rs_rx_trace[i] and in-turn from
trace.rx_trace_pos[i] in rds_recv_track_latency(),
with both arrays sized 3 (RDS_MSG_RX_DGRAM_TRACE_MAX). So fix the
off-by-one bounds check in rds_recv_track_latency() to prevent
a potential crash in rds_cmsg_recv().

Found by syzcaller:
=================================================================
UBSAN: array-index-out-of-bounds in net/rds/recv.c:585:39
index 4 is out of range for type 'u64 [4]'
CPU: 1 PID: 8058 Comm: syz-executor228 Not tainted 6.6.0-gd2f51b3516da #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS 1.15.0-1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x136/0x150 lib/dump_stack.c:106
 ubsan_epilogue lib/ubsan.c:217 [inline]
 __ubsan_handle_out_of_bounds+0xd5/0x130 lib/ubsan.c:348
 rds_cmsg_recv+0x60d/0x700 net/rds/recv.c:585
 rds_recvmsg+0x3fb/0x1610 net/rds/recv.c:716
 sock_recvmsg_nosec net/socket.c:1044 [inline]
 sock_recvmsg+0xe2/0x160 net/socket.c:1066
 __sys_recvfrom+0x1b6/0x2f0 net/socket.c:2246
 __do_sys_recvfrom net/socket.c:2264 [inline]
 __se_sys_recvfrom net/socket.c:2260 [inline]
 __x64_sys_recvfrom+0xe0/0x1b0 net/socket.c:2260
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b
==================================================================

The Linux kernel CVE team has assigned CVE-2024-26613 to this issue.


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

	Issue introduced in 4.11 with commit 3289025aedc0 and fixed in 4.19.307 with commit 344350bfa3b4
	Issue introduced in 4.11 with commit 3289025aedc0 and fixed in 5.4.269 with commit a37ae111db5e
	Issue introduced in 4.11 with commit 3289025aedc0 and fixed in 5.10.210 with commit 5ae8d5004463
	Issue introduced in 4.11 with commit 3289025aedc0 and fixed in 5.15.149 with commit 00d1ee8e1d02
	Issue introduced in 4.11 with commit 3289025aedc0 and fixed in 6.1.76 with commit 71024928b3f7
	Issue introduced in 4.11 with commit 3289025aedc0 and fixed in 6.6.15 with commit 7a73190ea557
	Issue introduced in 4.11 with commit 3289025aedc0 and fixed in 6.7.3 with commit 0b787c2dea15
	Issue introduced in 4.11 with commit 3289025aedc0 and fixed in 6.8-rc2 with commit 13e788deb734

Please see https://www.kernel.org or 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-2024-26613
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:
	net/rds/af_rds.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/344350bfa3b4b37d7c3d5a00536e6fbf0e953fbf
	https://git.kernel.org/stable/c/a37ae111db5e0f7e3d6b692056c30e3e0f6f79cd
	https://git.kernel.org/stable/c/5ae8d50044633306ff160fcf7faa24994175efe1
	https://git.kernel.org/stable/c/00d1ee8e1d02194f7b7b433e904e04bbcd2cc0dc
	https://git.kernel.org/stable/c/71024928b3f71ce4529426f8692943205c58d30b
	https://git.kernel.org/stable/c/7a73190ea557e7f26914b0fe04c1f57a96cb771f
	https://git.kernel.org/stable/c/0b787c2dea15e7a2828fa3a74a5447df4ed57711
	https://git.kernel.org/stable/c/13e788deb7348cc88df34bed736c3b3b9927ea52