Date: Tue, 12 Aug 2025 23:49:31 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 288826] Booting a Read-Only system with /entropy file panic it while reading it with dd Message-ID: <bug-288826-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=288826 Bug ID: 288826 Summary: Booting a Read-Only system with /entropy file panic it while reading it with dd Product: Base System Version: CURRENT Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: olivier@freebsd.org So, I’m using nanobsd that is using read-only /. Using fresh current from today. But while hacking it, I’ve switched it to read-write then restarted the system. -> So the RC script, during shutdown started save_dev_random() and because the RW / it was able to generate and write the file /entropy. But at the next start, while starting random_start() it try to read with dd this /entropy file from a Read-Only /, and this create a 100% reproducible panic created by dd: Fatal trap 12: page fault while in kernel mode cpuid = 6; apic id = 0c fault virtual address = 0x4 fault code = supervisor read data, page not present instruction pointer = 0x20:0xffffffff807d67ec stack pointer = 0x28:0xfffffe008db0cc70 frame pointer = 0x28:0xfffffe008db0cc90 code segment = base 0x0, limit 0xfffff, type 0x1b = DPL 0, pres 1, long 1, def32 0, gran 1 processor eflags = interrupt enabled, resume, IOPL = 0 current process = 275 (dd) rdi: ffffffff81a5cde4 rsi: 0000000000000040 rdx: 00000000000000b9 rcx: 0000000000000002 r8: 0000000000000000 r9: fffffe008db0ca92 rax: 0000000000000000 rbx: ffffffff81a5cde4 rbp: fffffe008db0cc90 r10: 0000000000000000 r11: f4539e9490d76bac r12: 000000000000000c r13: ffffffff807d67b0 r14: fffffe008db0cda8 r15: fffffe008db0ccb4 trap number = 12 panic: page fault cpuid = 6 time = 1755009441 KDB: stack backtrace: #0 0xffffffff809f6f2d at kdb_backtrace+0x5d #1 0xffffffff809adff6 at vpanic+0x136 #2 0xffffffff809adeb3 at panic+0x43 #3 0xffffffff80dccb29 at trap_pfault+0x3c9 #4 0xffffffff80da3a08 at calltrap+0x8 #5 0xffffffff807d5caf at randomdev_write+0x16f #6 0xffffffff808d4dba at devfs_write_f+0xda #7 0xffffffff80a18e76 at dofilewrite+0x66 #8 0xffffffff80a18997 at sys_write+0x127 #9 0xffffffff80dcd458 at amd64_syscall+0x118 -- You are receiving this mail because: You are the assignee for the bug.home | help
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