In cam/ctl.c, ctl_ioctl(), for CTL_PORT_REQ, if user code passes in a non-null req->result_nvl, but a null req->result, and fe->ioctl is zero, then ctl_ioctl() calls nvlist_destroy() with the user-supplied req->result_nvl. Here's a demo: int main() { int fd = open("/dev/cam/ctl", 2); char buf[256]; memset(buf, 0, sizeof(buf)); strcpy(buf, "camtgt"); // driver *(unsigned long long *)(buf+72) = 0x8000000000000000; // result_nvl ioctl(fd, 0xc100e126, buf); // CTL_PORT_REQ } # uname -a FreeBSD 14.0-CURRENT FreeBSD 14.0-CURRENT #40 main-n250928-b8170f38ccc7-dirty: Mon Aug 29 13:09:55 EDT 2022 rtm@xxx:/usr/obj/usr/rtm/symbsd/src/riscv.riscv64/sys/RTM riscv # cc x.c # ./a.out panic: Fatal page fault at 0xffffffc0000a9b16: 0x8000000000000000 panic() at panic+0x2a page_fault_handler() at page_fault_handler+0x1d6 do_trap_supervisor() at do_trap_supervisor+0x76 cpu_exception_handler_supervisor() at cpu_exception_handler_supervisor+0x70 --- exception 13, tval = 0x8000000000000000 nvlist_destroy() at nvlist_destroy+0x10 ctl_ioctl() at ctl_ioctl+0x183a devfs_ioctl() at devfs_ioctl+0xbe VOP_IOCTL_APV() at VOP_IOCTL_APV+0x30 VOP_IOCTL() at VOP_IOCTL+0x36 vn_ioctl() at vn_ioctl+0xba devfs_ioctl_f() at devfs_ioctl_f+0x20 fo_ioctl() at fo_ioctl+0xa kern_ioctl() at kern_ioctl+0x242 sys_ioctl() at sys_ioctl+0x120 syscallenter() at syscallenter+0xec ecall_handler() at ecall_handler+0x18 do_trap_user() at do_trap_user+0xea cpu_exception_handler_user() at cpu_exception_handler_user+0x72
Similarly, for a CTL_LUN_REQ ioctl, if the user program sets backend[] to "block", lun_req->result_nvl to e.g. 0x8000000000000000, and lun_req->result to NULL, backend->ioctl() (which is ctl_be_block_ioctl()) won't modify reslt_nvl, but ctl_ioctl() will call nvlist_destroy(lun_req->result_nvl), causing a crash.
I'll take a look shortly... but if somebody else has a patch sooner than I look at it so much the better.
This device is available only to root user, so it is a form of foot shooting. But OK, I'll patch it.
A commit in branch main references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=0586be48a97c5af50ba4f578d33211f81cc57016 commit 0586be48a97c5af50ba4f578d33211f81cc57016 Author: Alexander Motin <mav@FreeBSD.org> AuthorDate: 2022-09-07 01:58:27 +0000 Commit: Alexander Motin <mav@FreeBSD.org> CommitDate: 2022-09-07 01:58:27 +0000 CTL: Validate IOCTL parameters. It was possible to cause kernel panic by passing too large args_len or non-NULL result_nvl. Though since the /dev/cam/ctl device is accessible only by root and used only by limited number of tools it was not a big problem. PR: 266115 PR: 266136 Reported by: Robert Morris <rtm@lcs.mit.edu> MFC after: 1 week sys/cam/ctl/ctl.c | 14 ++++++++++++++ sys/cam/ctl/ctl_ioctl.h | 1 + 2 files changed, 15 insertions(+)
A commit in branch stable/13 references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=c48d0754a05334cacbe6cd34871c10f3ef6f4d56 commit c48d0754a05334cacbe6cd34871c10f3ef6f4d56 Author: Alexander Motin <mav@FreeBSD.org> AuthorDate: 2022-09-07 01:58:27 +0000 Commit: Alexander Motin <mav@FreeBSD.org> CommitDate: 2022-09-14 17:27:04 +0000 CTL: Validate IOCTL parameters. It was possible to cause kernel panic by passing too large args_len or non-NULL result_nvl. Though since the /dev/cam/ctl device is accessible only by root and used only by limited number of tools it was not a big problem. PR: 266115 PR: 266136 Reported by: Robert Morris <rtm@lcs.mit.edu> MFC after: 1 week (cherry picked from commit 0586be48a97c5af50ba4f578d33211f81cc57016) sys/cam/ctl/ctl.c | 14 ++++++++++++++ sys/cam/ctl/ctl_ioctl.h | 1 + 2 files changed, 15 insertions(+)
A commit in branch stable/12 references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=ce1895b7248d5601b34d0d6492539a7081a8d451 commit ce1895b7248d5601b34d0d6492539a7081a8d451 Author: Alexander Motin <mav@FreeBSD.org> AuthorDate: 2022-09-07 01:58:27 +0000 Commit: Alexander Motin <mav@FreeBSD.org> CommitDate: 2022-09-14 17:28:18 +0000 CTL: Validate IOCTL parameters. It was possible to cause kernel panic by passing too large args_len or non-NULL result_nvl. Though since the /dev/cam/ctl device is accessible only by root and used only by limited number of tools it was not a big problem. PR: 266115 PR: 266136 Reported by: Robert Morris <rtm@lcs.mit.edu> MFC after: 1 week (cherry picked from commit 0586be48a97c5af50ba4f578d33211f81cc57016) sys/cam/ctl/ctl.c | 14 ++++++++++++++ sys/cam/ctl/ctl_ioctl.h | 1 + 2 files changed, 15 insertions(+)