From a5f7a5bb3b7f28ba7e4fa246775b29a0e5537255 Mon Sep 17 00:00:00 2001 From: Jinke Han Date: Tue, 8 Sep 2026 15:37:42 +0800 Subject: x86/kprobes: Fix crash when probing CS CALL instructions When using eBPF to probe CS CALL instructions within a function, a crash can be triggered. The eBPF tool probes offset 257 of the __hrtimer_run_queues() function: <__hrtimer_run_queues+249>: nopl 0x0(%rax,%rax,1) <__hrtimer_run_queues+254>: mov %r14,%rdi <__hrtimer_run_queues+257>: cs call <__x86_indirect_thunk_r12> <__hrtimer_run_queues+263>: mov %eax,%r12d <__hrtimer_run_queues+266>: xchg %ax,%ax <__hrtimer_run_queues+268>: mov %r13,%rdi Which triggers this crash: BUG: unable to handle page fault for address: 00000000000f41c9 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: 0002 [#1] SMP NOPTI CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P RIP: 0010:__hrtimer_run_queues+0x106/0x230 Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is at the 6th byte of the above CS CALL instruction. Since the CS CALL instruction occupies 6 bytes, the exception occurred in the middle of that call instruction. The root cause is that when using eBPF tools to probe in the middle of a function, a kprobe with INT3 is used as the underlying implementation. During single-step emulation of the original CALL instruction, int3_emulate_call() assumes that the probed CALL instruction is 5 bytes long. However, the actual CS-prefixed CALL instruction occupies 6 bytes, so it constructs an incorrect exception return address. When the CPU returns from the kprobe handler, the next instruction to be executed is at the address of the last byte of that CS CALL instruction. Coincidentally, starting from that address, the CPU fetches and decodes a completely different instruction, which ultimately triggers a kernel crash. Fix the issue by using the actual instruction length obtained from the instruction decoder when constructing the exception return address, rather than relying on the hardcoded CALL_INSN_SIZE macro. [ mingo: Refined the changelog ] Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step") Suggested-by: Masami Hiramatsu (Google) Signed-off-by: Jinke Han Signed-off-by: Ingo Molnar Reviewed-by: Masami Hiramatsu (Google) Acked-by: Yafang Shao Acked-by: Borislav Petkov Cc: Peter Zijlstra Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000 --- drivers/scsi/nsp32_debug.c | 263 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 263 insertions(+) create mode 100644 drivers/scsi/nsp32_debug.c (limited to 'drivers/scsi/nsp32_debug.c') diff --git a/drivers/scsi/nsp32_debug.c b/drivers/scsi/nsp32_debug.c new file mode 100644 index 000000000..4f1d4bf9c --- /dev/null +++ b/drivers/scsi/nsp32_debug.c @@ -0,0 +1,263 @@ +/* + * Workbit NinjaSCSI-32Bi/UDE PCI/CardBus SCSI Host Bus Adapter driver + * Debug routine + * + * This software may be used and distributed according to the terms of + * the GNU General Public License. + */ + +/* + * Show the command data of a command + */ +static const char unknown[] = "UNKNOWN"; + +static const char * group_0_commands[] = { +/* 00-03 */ "Test Unit Ready", "Rezero Unit", unknown, "Request Sense", +/* 04-07 */ "Format Unit", "Read Block Limits", unknown, "Reassign Blocks", +/* 08-0d */ "Read (6)", unknown, "Write (6)", "Seek (6)", unknown, unknown, +/* 0e-12 */ unknown, "Read Reverse", "Write Filemarks", "Space", "Inquiry", +/* 13-16 */ unknown, "Recover Buffered Data", "Mode Select", "Reserve", +/* 17-1b */ "Release", "Copy", "Erase", "Mode Sense", "Start/Stop Unit", +/* 1c-1d */ "Receive Diagnostic", "Send Diagnostic", +/* 1e-1f */ "Prevent/Allow Medium Removal", unknown, +}; + + +static const char *group_1_commands[] = { +/* 20-22 */ unknown, unknown, unknown, +/* 23-28 */ unknown, unknown, "Read Capacity", unknown, unknown, "Read (10)", +/* 29-2d */ unknown, "Write (10)", "Seek (10)", unknown, unknown, +/* 2e-31 */ "Write Verify","Verify", "Search High", "Search Equal", +/* 32-34 */ "Search Low", "Set Limits", "Prefetch or Read Position", +/* 35-37 */ "Synchronize Cache","Lock/Unlock Cache", "Read Defect Data", +/* 38-3c */ "Medium Scan", "Compare","Copy Verify", "Write Buffer", "Read Buffer", +/* 3d-3f */ "Update Block", "Read Long", "Write Long", +}; + + +static const char *group_2_commands[] = { +/* 40-41 */ "Change Definition", "Write Same", +/* 42-48 */ "Read Sub-Ch(cd)", "Read TOC", "Read Header(cd)", "Play Audio(cd)", unknown, "Play Audio MSF(cd)", "Play Audio Track/Index(cd)", +/* 49-4f */ "Play Track Relative(10)(cd)", unknown, "Pause/Resume(cd)", "Log Select", "Log Sense", unknown, unknown, +/* 50-55 */ unknown, unknown, unknown, unknown, unknown, "Mode Select (10)", +/* 56-5b */ unknown, unknown, unknown, unknown, "Mode Sense (10)", unknown, +/* 5c-5f */ unknown, unknown, unknown, +}; + +#define group(opcode) (((opcode) >> 5) & 7) + +#define RESERVED_GROUP 0 +#define VENDOR_GROUP 1 +#define NOTEXT_GROUP 2 + +static const char **commands[] = { + group_0_commands, group_1_commands, group_2_commands, + (const char **) RESERVED_GROUP, (const char **) RESERVED_GROUP, + (const char **) NOTEXT_GROUP, (const char **) VENDOR_GROUP, + (const char **) VENDOR_GROUP +}; + +static const char reserved[] = "RESERVED"; +static const char vendor[] = "VENDOR SPECIFIC"; + +static void print_opcodek(unsigned char opcode) +{ + const char **table = commands[ group(opcode) ]; + + switch ((unsigned long) table) { + case RESERVED_GROUP: + printk("%s[%02x] ", reserved, opcode); + break; + case NOTEXT_GROUP: + printk("%s(notext)[%02x] ", unknown, opcode); + break; + case VENDOR_GROUP: + printk("%s[%02x] ", vendor, opcode); + break; + default: + if (table[opcode & 0x1f] != unknown) + printk("%s[%02x] ", table[opcode & 0x1f], opcode); + else + printk("%s[%02x] ", unknown, opcode); + break; + } +} + +static void print_commandk (unsigned char *command) +{ + int i,s; +// printk(KERN_DEBUG); + print_opcodek(command[0]); + /*printk(KERN_DEBUG "%s ", __func__);*/ + if ((command[0] >> 5) == 6 || + (command[0] >> 5) == 7 ) { + s = 12; /* vender specific */ + } else { + s = COMMAND_SIZE(command[0]); + } + + for ( i = 1; i < s; ++i) { + printk("%02x ", command[i]); + } + + switch (s) { + case 6: + printk("LBA=%d len=%d", + (((unsigned int)command[1] & 0x0f) << 16) | + ( (unsigned int)command[2] << 8) | + ( (unsigned int)command[3] ), + (unsigned int)command[4] + ); + break; + case 10: + printk("LBA=%d len=%d", + ((unsigned int)command[2] << 24) | + ((unsigned int)command[3] << 16) | + ((unsigned int)command[4] << 8) | + ((unsigned int)command[5] ), + ((unsigned int)command[7] << 8) | + ((unsigned int)command[8] ) + ); + break; + case 12: + printk("LBA=%d len=%d", + ((unsigned int)command[2] << 24) | + ((unsigned int)command[3] << 16) | + ((unsigned int)command[4] << 8) | + ((unsigned int)command[5] ), + ((unsigned int)command[6] << 24) | + ((unsigned int)command[7] << 16) | + ((unsigned int)command[8] << 8) | + ((unsigned int)command[9] ) + ); + break; + default: + break; + } + printk("\n"); +} + +static void show_command(struct scsi_cmnd *SCpnt) +{ + print_commandk(SCpnt->cmnd); +} + +static void show_busphase(unsigned char stat) +{ + switch(stat) { + case BUSPHASE_COMMAND: + printk( "BUSPHASE_COMMAND\n"); + break; + case BUSPHASE_MESSAGE_IN: + printk( "BUSPHASE_MESSAGE_IN\n"); + break; + case BUSPHASE_MESSAGE_OUT: + printk( "BUSPHASE_MESSAGE_OUT\n"); + break; + case BUSPHASE_DATA_IN: + printk( "BUSPHASE_DATA_IN\n"); + break; + case BUSPHASE_DATA_OUT: + printk( "BUSPHASE_DATA_OUT\n"); + break; + case BUSPHASE_STATUS: + printk( "BUSPHASE_STATUS\n"); + break; + case BUSPHASE_SELECT: + printk( "BUSPHASE_SELECT\n"); + break; + default: + printk( "BUSPHASE_other: 0x%x\n", stat); + break; + } +} + +static void show_autophase(unsigned short i) +{ + printk("auto: 0x%x,", i); + + if(i & COMMAND_PHASE) { + printk(" cmd"); + } + if(i & DATA_IN_PHASE) { + printk(" din"); + } + if(i & DATA_OUT_PHASE) { + printk(" dout"); + } + if(i & MSGOUT_PHASE) { + printk(" mout"); + } + if(i & STATUS_PHASE) { + printk(" stat"); + } + if(i & ILLEGAL_PHASE) { + printk(" ill"); + } + if(i & BUS_FREE_OCCUER) { + printk(" bfree-o"); + } + if(i & MSG_IN_OCCUER) { + printk(" min-o"); + } + if(i & MSG_OUT_OCCUER) { + printk(" mout-o"); + } + if(i & SELECTION_TIMEOUT) { + printk(" sel"); + } + if(i & MSGIN_00_VALID) { + printk(" m0"); + } + if(i & MSGIN_02_VALID) { + printk(" m2"); + } + if(i & MSGIN_03_VALID) { + printk(" m3"); + } + if(i & MSGIN_04_VALID) { + printk(" m4"); + } + if(i & AUTOSCSI_BUSY) { + printk(" busy"); + } + + printk("\n"); +} + +static void nsp32_print_register(int base) +{ + if (!(NSP32_DEBUG_MASK & NSP32_SPECIAL_PRINT_REGISTER)) + return; + + printk("Phase=0x%x, ", nsp32_read1(base, SCSI_BUS_MONITOR)); + printk("OldPhase=0x%x, ", nsp32_index_read1(base, OLD_SCSI_PHASE)); + printk("syncreg=0x%x, ", nsp32_read1(base, SYNC_REG)); + printk("ackwidth=0x%x, ", nsp32_read1(base, ACK_WIDTH)); + printk("sgtpaddr=0x%lx, ", nsp32_read4(base, SGT_ADR)); + printk("scsioutlatch=0x%x, ", nsp32_read1(base, SCSI_OUT_LATCH_TARGET_ID)); + printk("msgout=0x%lx, ", nsp32_read4(base, SCSI_MSG_OUT)); + printk("miscrd=0x%x, ", nsp32_index_read2(base, MISC_WR)); + printk("seltimeout=0x%x, ", nsp32_read2(base, SEL_TIME_OUT)); + printk("sreqrate=0x%x, ", nsp32_read1(base, SREQ_SMPL_RATE)); + printk("transStatus=0x%x, ", nsp32_read2(base, TRANSFER_STATUS)); + printk("reselectid=0x%x, ", nsp32_read2(base, COMMAND_CONTROL)); + printk("arbit=0x%x, ", nsp32_read1(base, ARBIT_STATUS)); + printk("BmStart=0x%lx, ", nsp32_read4(base, BM_START_ADR)); + printk("BmCount=0x%lx, ", nsp32_read4(base, BM_CNT)); + printk("SackCnt=0x%lx, ", nsp32_read4(base, SACK_CNT)); + printk("SReqCnt=0x%lx, ", nsp32_read4(base, SREQ_CNT)); + printk("SavedSackCnt=0x%lx, ", nsp32_read4(base, SAVED_SACK_CNT)); + printk("ScsiBusControl=0x%x, ", nsp32_read1(base, SCSI_BUS_CONTROL)); + printk("FifoRestCnt=0x%x, ", nsp32_read2(base, FIFO_REST_CNT)); + printk("CdbIn=0x%x, ", nsp32_read1(base, SCSI_CSB_IN)); + printk("\n"); + + if (0) { + printk("execph=0x%x, ", nsp32_read2(base, SCSI_EXECUTE_PHASE)); + printk("IrqStatus=0x%x, ", nsp32_read2(base, IRQ_STATUS)); + printk("\n"); + } +} + +/* end */ -- cgit v1.3.1