9dbe086c69
A crash was found when dumping SMC-R connections. It can be reproduced by following steps: - environment: two RNICs on both sides. - run SMC-R between two sides, now a SMC_LGR_SYMMETRIC type link group will be created. - set the first RNIC down on either side and link group will turn to SMC_LGR_ASYMMETRIC_LOCAL then. - run 'smcss -R' and the crash will be triggered. BUG: kernel NULL pointer dereference, address: 0000000000000010 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 8000000101fdd067 P4D 8000000101fdd067 PUD 10ce46067 PMD 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 3 PID: 1810 Comm: smcss Kdump: loaded Tainted: G W E 6.7.0-rc6+ #51 RIP: 0010:__smc_diag_dump.constprop.0+0x36e/0x620 [smc_diag] Call Trace: <TASK> ? __die+0x24/0x70 ? page_fault_oops+0x66/0x150 ? exc_page_fault+0x69/0x140 ? asm_exc_page_fault+0x26/0x30 ? __smc_diag_dump.constprop.0+0x36e/0x620 [smc_diag] smc_diag_dump_proto+0xd0/0xf0 [smc_diag] smc_diag_dump+0x26/0x60 [smc_diag] netlink_dump+0x19f/0x320 __netlink_dump_start+0x1dc/0x300 smc_diag_handler_dump+0x6a/0x80 [smc_diag] ? __pfx_smc_diag_dump+0x10/0x10 [smc_diag] sock_diag_rcv_msg+0x121/0x140 ? __pfx_sock_diag_rcv_msg+0x10/0x10 netlink_rcv_skb+0x5a/0x110 sock_diag_rcv+0x28/0x40 netlink_unicast+0x22a/0x330 netlink_sendmsg+0x240/0x4a0 __sock_sendmsg+0xb0/0xc0 ____sys_sendmsg+0x24e/0x300 ? copy_msghdr_from_user+0x62/0x80 ___sys_sendmsg+0x7c/0xd0 ? __do_fault+0x34/0x1a0 ? do_read_fault+0x5f/0x100 ? do_fault+0xb0/0x110 __sys_sendmsg+0x4d/0x80 do_syscall_64+0x45/0xf0 entry_SYSCALL_64_after_hwframe+0x6e/0x76 When the first RNIC is set down, the lgr->lnk[0] will be cleared and an asymmetric link will be allocated in lgr->link[SMC_LINKS_PER_LGR_MAX - 1] by smc_llc_alloc_alt_link(). Then when we try to dump SMC-R connections in __smc_diag_dump(), the invalid lgr->lnk[0] will be accessed, resulting in this issue. So fix it by accessing the right link. Fixes: f16a7dd5cf27 ("smc: netlink interface for SMC sockets") Reported-by: henaumars <henaumars@sina.com> Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=7616 Signed-off-by: Wen Gu <guwen@linux.alibaba.com> Reviewed-by: Tony Lu <tonylu@linux.alibaba.com> Link: https://lore.kernel.org/r/1703662835-53416-1-git-send-email-guwen@linux.alibaba.com 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.