CVE-2023-54112

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> kcm: Fix memory leak in error path of kcm_sendmsg()<br /> <br /> syzbot reported a memory leak like below:<br /> <br /> BUG: memory leak<br /> unreferenced object 0xffff88810b088c00 (size 240):<br /> comm "syz-executor186", pid 5012, jiffies 4294943306 (age 13.680s)<br /> hex dump (first 32 bytes):<br /> 00 89 08 0b 81 88 ff ff 00 00 00 00 00 00 00 00 ................<br /> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................<br /> backtrace:<br /> [] __alloc_skb+0x1ef/0x230 net/core/skbuff.c:634<br /> [] alloc_skb include/linux/skbuff.h:1289 [inline]<br /> [] kcm_sendmsg+0x269/0x1050 net/kcm/kcmsock.c:815<br /> [] sock_sendmsg_nosec net/socket.c:725 [inline]<br /> [] sock_sendmsg+0x56/0xb0 net/socket.c:748<br /> [] ____sys_sendmsg+0x365/0x470 net/socket.c:2494<br /> [] ___sys_sendmsg+0xc9/0x130 net/socket.c:2548<br /> [] __sys_sendmsg+0xa6/0x120 net/socket.c:2577<br /> [] do_syscall_x64 arch/x86/entry/common.c:50 [inline]<br /> [] do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80<br /> [] entry_SYSCALL_64_after_hwframe+0x63/0xcd<br /> <br /> In kcm_sendmsg(), kcm_tx_msg(head)-&gt;last_skb is used as a cursor to append<br /> newly allocated skbs to &amp;#39;head&amp;#39;. If some bytes are copied, an error occurred,<br /> and jumped to out_error label, &amp;#39;last_skb&amp;#39; is left unmodified. A later<br /> kcm_sendmsg() will use an obsoleted &amp;#39;last_skb&amp;#39; reference, corrupting the<br /> &amp;#39;head&amp;#39; frag_list and causing the leak.<br /> <br /> This patch fixes this issue by properly updating the last allocated skb in<br /> &amp;#39;last_skb&amp;#39;.