GHSA-6f5g-233w-v625

Описание

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: __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