a0ade8404c
syzkaller found a warning in packet_getname() [0], where we try to copy 16 bytes to sockaddr_ll.sll_addr[8]. Some devices (ip6gre, vti6, ip6tnl) have 16 bytes address expressed by struct in6_addr. Also, Infiniband has 32 bytes as MAX_ADDR_LEN. The write seems to overflow, but actually not since we use struct sockaddr_storage defined in __sys_getsockname() and its size is 128 (_K_SS_MAXSIZE) bytes. Thus, we have sufficient room after sll_addr[] as __data[]. To avoid the warning, let's add a flex array member union-ed with sll_addr. Another option would be to use strncpy() and limit the copied length to sizeof(sll_addr), but it will return the partial address and break an application that passes sockaddr_storage to getsockname(). [0]: memcpy: detected field-spanning write (size 16) of single field "sll->sll_addr" at net/packet/af_packet.c:3604 (size 8) WARNING: CPU: 0 PID: 255 at net/packet/af_packet.c:3604 packet_getname+0x25c/0x3a0 net/packet/af_packet.c:3604 Modules linked in: CPU: 0 PID: 255 Comm: syz-executor750 Not tainted 6.5.0-rc1-00330-g60cc1f7d0605 #4 Hardware name: linux,dummy-virt (DT) pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : packet_getname+0x25c/0x3a0 net/packet/af_packet.c:3604 lr : packet_getname+0x25c/0x3a0 net/packet/af_packet.c:3604 sp : ffff800089887bc0 x29: ffff800089887bc0 x28: ffff000010f80f80 x27: 0000000000000003 x26: dfff800000000000 x25: ffff700011310f80 x24: ffff800087d55000 x23: dfff800000000000 x22: ffff800089887c2c x21: 0000000000000010 x20: ffff00000de08310 x19: ffff800089887c20 x18: ffff800086ab1630 x17: 20646c6569662065 x16: 6c676e697320666f x15: 0000000000000001 x14: 1fffe0000d56d7ca x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000000000 x10: 0000000000000000 x9 : 3e60944c3da92b00 x8 : 3e60944c3da92b00 x7 : 0000000000000001 x6 : 0000000000000001 x5 : ffff8000898874f8 x4 : ffff800086ac99e0 x3 : ffff8000803f8808 x2 : 0000000000000001 x1 : 0000000100000000 x0 : 0000000000000000 Call trace: packet_getname+0x25c/0x3a0 net/packet/af_packet.c:3604 __sys_getsockname+0x168/0x24c net/socket.c:2042 __do_sys_getsockname net/socket.c:2057 [inline] __se_sys_getsockname net/socket.c:2054 [inline] __arm64_sys_getsockname+0x7c/0x94 net/socket.c:2054 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x134/0x240 arch/arm64/kernel/syscall.c:139 do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:188 el0_svc+0x2c/0x7c arch/arm64/kernel/entry-common.c:647 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:665 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591 Fixes: df8fc4e934c1 ("kbuild: Enable -fstrict-flex-arrays=3") Reported-by: syzkaller <syzkaller@googlegroups.com> Suggested-by: Kees Cook <keescook@chromium.org> Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Link: https://lore.kernel.org/r/20230724213425.22920-3-kuniyu@amazon.com Reviewed-by: Simon Horman <simon.horman@corigine.com> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.