* UBSAN: array-index-out-of-bounds in arch_uprobe_analyze_insn @ 2020-09-20 23:02 syzbot 2020-09-21 0:13 ` syzbot 2020-09-22 4:20 ` syzbot 0 siblings, 2 replies; 5+ messages in thread From: syzbot @ 2020-09-20 23:02 UTC (permalink / raw) To: bp, gustavoars, hpa, linux-kernel, mingo, syzkaller-bugs, tglx, wang.yi59, x86 Hello, syzbot found the following issue on: HEAD commit: 325d0eab Merge branch 'akpm' (patches from Andrew) git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=1195f481900000 kernel config: https://syzkaller.appspot.com/x/.config?x=b12e84189082991c dashboard link: https://syzkaller.appspot.com/bug?extid=9b64b619f10f19d19a7c compiler: gcc (GCC) 10.1.0-syz 20200507 Unfortunately, I don't have any reproducer for this issue yet. IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+9b64b619f10f19d19a7c@syzkaller.appspotmail.com ================================================================================ UBSAN: array-index-out-of-bounds in arch/x86/kernel/uprobes.c:263:56 index 4 is out of range for type 'insn_byte_t [4]' CPU: 1 PID: 22315 Comm: syz-executor.4 Not tainted 5.9.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x198/0x1fd lib/dump_stack.c:118 ubsan_epilogue+0xb/0x5a lib/ubsan.c:148 __ubsan_handle_out_of_bounds.cold+0x62/0x6c lib/ubsan.c:356 is_prefix_bad arch/x86/kernel/uprobes.c:263 [inline] uprobe_init_insn arch/x86/kernel/uprobes.c:286 [inline] arch_uprobe_analyze_insn+0x8f4/0xa40 arch/x86/kernel/uprobes.c:856 prepare_uprobe kernel/events/uprobes.c:860 [inline] install_breakpoint.isra.0+0x6c4/0x7c0 kernel/events/uprobes.c:903 uprobe_mmap+0x5ec/0x1080 kernel/events/uprobes.c:1394 mmap_region+0x5cf/0x1780 mm/mmap.c:1839 do_mmap+0xcf9/0x11d0 mm/mmap.c:1545 vm_mmap_pgoff+0x195/0x200 mm/util.c:506 ksys_mmap_pgoff+0x444/0x580 mm/mmap.c:1596 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45d5f9 Code: 5d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 2b b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f8e919bcc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 0000000000020f80 RCX: 000000000045d5f9 RDX: 0000000000000000 RSI: 0000000000003000 RDI: 0000000020007000 RBP: 000000000118cf98 R08: 0000000000000003 R09: 0000000000000000 R10: 0000000000000412 R11: 0000000000000246 R12: 000000000118cf4c R13: 00007ffe8fbd4c5f R14: 00007f8e919bd9c0 R15: 000000000118cf4c ================================================================================ --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: UBSAN: array-index-out-of-bounds in arch_uprobe_analyze_insn 2020-09-20 23:02 UBSAN: array-index-out-of-bounds in arch_uprobe_analyze_insn syzbot @ 2020-09-21 0:13 ` syzbot 2020-09-22 4:20 ` syzbot 1 sibling, 0 replies; 5+ messages in thread From: syzbot @ 2020-09-21 0:13 UTC (permalink / raw) To: bp, gustavoars, hpa, linux-kernel, mingo, syzkaller-bugs, tglx, wang.yi59, x86 syzbot has found a reproducer for the following issue on: HEAD commit: 325d0eab Merge branch 'akpm' (patches from Andrew) git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=14e69c03900000 kernel config: https://syzkaller.appspot.com/x/.config?x=b12e84189082991c dashboard link: https://syzkaller.appspot.com/bug?extid=9b64b619f10f19d19a7c compiler: gcc (GCC) 10.1.0-syz 20200507 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1573a8ad900000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=164ee6c5900000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+9b64b619f10f19d19a7c@syzkaller.appspotmail.com ================================================================================ UBSAN: array-index-out-of-bounds in arch/x86/kernel/uprobes.c:263:56 index 4 is out of range for type 'insn_byte_t [4]' CPU: 0 PID: 6870 Comm: syz-executor876 Not tainted 5.9.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x198/0x1fd lib/dump_stack.c:118 ubsan_epilogue+0xb/0x5a lib/ubsan.c:148 __ubsan_handle_out_of_bounds.cold+0x62/0x6c lib/ubsan.c:356 is_prefix_bad arch/x86/kernel/uprobes.c:263 [inline] uprobe_init_insn arch/x86/kernel/uprobes.c:286 [inline] arch_uprobe_analyze_insn+0x8f4/0xa40 arch/x86/kernel/uprobes.c:856 prepare_uprobe kernel/events/uprobes.c:860 [inline] install_breakpoint.isra.0+0x6c4/0x7c0 kernel/events/uprobes.c:903 uprobe_mmap+0x5ec/0x1080 kernel/events/uprobes.c:1394 mmap_region+0x5cf/0x1780 mm/mmap.c:1839 do_mmap+0xcf9/0x11d0 mm/mmap.c:1545 vm_mmap_pgoff+0x195/0x200 mm/util.c:506 ksys_mmap_pgoff+0x444/0x580 mm/mmap.c:1596 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x440379 Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ffc6ed13058 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000440379 RDX: 0000000000000000 RSI: 0000000000003000 RDI: 0000000020007000 RBP: 00000000006ca018 R08: 0000000000000003 R09: 0000000000000000 R10: 0000000000000412 R11: 0000000000000246 R12: 0000000000401b80 R13: 0000000000401c10 R14: 0000000000000000 R15: 0000000000000000 ================================================================================ ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: UBSAN: array-index-out-of-bounds in arch_uprobe_analyze_insn 2020-09-20 23:02 UBSAN: array-index-out-of-bounds in arch_uprobe_analyze_insn syzbot 2020-09-21 0:13 ` syzbot @ 2020-09-22 4:20 ` syzbot 2020-12-02 0:48 ` Kees Cook 1 sibling, 1 reply; 5+ messages in thread From: syzbot @ 2020-09-22 4:20 UTC (permalink / raw) To: akpm, bp, coreteam, davem, gustavoars, hpa, john.stultz, kaber, kadlec, keescook, linux-kernel, mingo, netdev, netfilter-devel, pablo, syzkaller-bugs, tglx, torvalds, wang.yi59, x86 syzbot has bisected this issue to: commit 4b2bd5fec007a4fd3fc82474b9199af25013de4c Author: John Stultz <john.stultz@linaro.org> Date: Sat Oct 8 00:02:33 2016 +0000 proc: fix timerslack_ns CAP_SYS_NICE check when adjusting self bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1697348d900000 start commit: 325d0eab Merge branch 'akpm' (patches from Andrew) git tree: upstream final oops: https://syzkaller.appspot.com/x/report.txt?x=1597348d900000 console output: https://syzkaller.appspot.com/x/log.txt?x=1197348d900000 kernel config: https://syzkaller.appspot.com/x/.config?x=b12e84189082991c dashboard link: https://syzkaller.appspot.com/bug?extid=9b64b619f10f19d19a7c syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1573a8ad900000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=164ee6c5900000 Reported-by: syzbot+9b64b619f10f19d19a7c@syzkaller.appspotmail.com Fixes: 4b2bd5fec007 ("proc: fix timerslack_ns CAP_SYS_NICE check when adjusting self") For information about bisection process see: https://goo.gl/tpsmEJ#bisection ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: UBSAN: array-index-out-of-bounds in arch_uprobe_analyze_insn 2020-09-22 4:20 ` syzbot @ 2020-12-02 0:48 ` Kees Cook 2020-12-02 6:12 ` Masami Hiramatsu 0 siblings, 1 reply; 5+ messages in thread From: Kees Cook @ 2020-12-02 0:48 UTC (permalink / raw) To: Masami Hiramatsu, Srikar Dronamraju, Ricardo Neri Cc: akpm, bp, coreteam, syzbot, davem, gustavoars, hpa, john.stultz, kaber, kadlec, linux-kernel, mingo, netdev, netfilter-devel, pablo, syzkaller-bugs, tglx, torvalds, wang.yi59, x86 Hi, There appears to be a problem with prefix counting for the instruction decoder. It looks like insn_get_prefixes() isn't keeping "nb" and "nbytes" in sync correctly: while (inat_is_legacy_prefix(attr)) { /* Skip if same prefix */ for (i = 0; i < nb; i++) if (prefixes->bytes[i] == b) goto found; if (nb == 4) /* Invalid instruction */ break; prefixes->bytes[nb++] = b; ... found: prefixes->nbytes++; insn->next_byte++; lb = b; b = peek_next(insn_byte_t, insn); attr = inat_get_opcode_attribute(b); } (nbytes is incremented on repeated prefixes, but "nb" isn't) However, it looks like nbytes is used as an offset: static inline int insn_offset_rex_prefix(struct insn *insn) { return insn->prefixes.nbytes; } static inline int insn_offset_vex_prefix(struct insn *insn) { return insn_offset_rex_prefix(insn) + insn->rex_prefix.nbytes; } Which means everything that iterates over prefixes.bytes[] is buggy, since they may be trying to read past the end of the array: $ git grep -A3 -E '< .*prefixes(\.|->)nbytes' boot/compressed/sev-es.c: for (i = 0; i < insn->prefixes.nbytes; i++) { boot/compressed/sev-es.c- insn_byte_t p = insn->prefixes.bytes[i]; boot/compressed/sev-es.c- boot/compressed/sev-es.c- if (p == 0xf2 || p == 0xf3) -- kernel/uprobes.c: for (i = 0; i < insn->prefixes.nbytes; i++) { kernel/uprobes.c- insn_attr_t attr; kernel/uprobes.c- kernel/uprobes.c- attr = inat_get_opcode_attribute(insn->prefixes.bytes[i]); -- kernel/uprobes.c: for (i = 0; i < insn->prefixes.nbytes; i++) { kernel/uprobes.c- if (insn->prefixes.bytes[i] == 0x66) kernel/uprobes.c- return -ENOTSUPP; kernel/uprobes.c- } -- lib/insn-eval.c: for (i = 0; i < insn->prefixes.nbytes; i++) { lib/insn-eval.c- insn_byte_t p = insn->prefixes.bytes[i]; lib/insn-eval.c- lib/insn-eval.c- if (p == 0xf2 || p == 0xf3) -- lib/insn-eval.c: for (i = 0; i < insn->prefixes.nbytes; i++) { lib/insn-eval.c- insn_attr_t attr; lib/insn-eval.c- lib/insn-eval.c- attr = inat_get_opcode_attribute(insn->prefixes.bytes[i]); I don't see a clear way to fix this. -Kees On Mon, Sep 21, 2020 at 09:20:07PM -0700, syzbot wrote: > syzbot has bisected this issue to: > > commit 4b2bd5fec007a4fd3fc82474b9199af25013de4c > Author: John Stultz <john.stultz@linaro.org> > Date: Sat Oct 8 00:02:33 2016 +0000 > > proc: fix timerslack_ns CAP_SYS_NICE check when adjusting self > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1697348d900000 > start commit: 325d0eab Merge branch 'akpm' (patches from Andrew) > git tree: upstream > final oops: https://syzkaller.appspot.com/x/report.txt?x=1597348d900000 > console output: https://syzkaller.appspot.com/x/log.txt?x=1197348d900000 > kernel config: https://syzkaller.appspot.com/x/.config?x=b12e84189082991c > dashboard link: https://syzkaller.appspot.com/bug?extid=9b64b619f10f19d19a7c > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1573a8ad900000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=164ee6c5900000 > > Reported-by: syzbot+9b64b619f10f19d19a7c@syzkaller.appspotmail.com > Fixes: 4b2bd5fec007 ("proc: fix timerslack_ns CAP_SYS_NICE check when adjusting self") > > For information about bisection process see: https://goo.gl/tpsmEJ#bisection -- Kees Cook ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: UBSAN: array-index-out-of-bounds in arch_uprobe_analyze_insn 2020-12-02 0:48 ` Kees Cook @ 2020-12-02 6:12 ` Masami Hiramatsu 0 siblings, 0 replies; 5+ messages in thread From: Masami Hiramatsu @ 2020-12-02 6:12 UTC (permalink / raw) To: Kees Cook Cc: Srikar Dronamraju, Ricardo Neri, akpm, bp, coreteam, syzbot, davem, gustavoars, hpa, john.stultz, kaber, kadlec, linux-kernel, mingo, netdev, netfilter-devel, pablo, syzkaller-bugs, tglx, torvalds, wang.yi59, x86 Hi Kees, On Tue, 1 Dec 2020 16:48:55 -0800 Kees Cook <keescook@chromium.org> wrote: > Hi, > > There appears to be a problem with prefix counting for the instruction > decoder. It looks like insn_get_prefixes() isn't keeping "nb" and "nbytes" > in sync correctly: > > while (inat_is_legacy_prefix(attr)) { > /* Skip if same prefix */ > for (i = 0; i < nb; i++) > if (prefixes->bytes[i] == b) > goto found; > if (nb == 4) > /* Invalid instruction */ > break; > prefixes->bytes[nb++] = b; > ... > found: > prefixes->nbytes++; > insn->next_byte++; > lb = b; > b = peek_next(insn_byte_t, insn); > attr = inat_get_opcode_attribute(b); > } > > (nbytes is incremented on repeated prefixes, but "nb" isn't) > > However, it looks like nbytes is used as an offset: > > static inline int insn_offset_rex_prefix(struct insn *insn) > { > return insn->prefixes.nbytes; > } > static inline int insn_offset_vex_prefix(struct insn *insn) > { > return insn_offset_rex_prefix(insn) + insn->rex_prefix.nbytes; > } Yes, it is designed to do that. nbytes counts how many bytes the prefix is, and nb is how many bytes of the prefix->bytes consumed. Since the legacy prefix can be repeated and more than 4 (bytes), we can not store all of those. > > Which means everything that iterates over prefixes.bytes[] is buggy, > since they may be trying to read past the end of the array: Good catch! All following usage are wrong... > > $ git grep -A3 -E '< .*prefixes(\.|->)nbytes' > boot/compressed/sev-es.c: for (i = 0; i < insn->prefixes.nbytes; i++) { > boot/compressed/sev-es.c- insn_byte_t p = > insn->prefixes.bytes[i]; > boot/compressed/sev-es.c- > boot/compressed/sev-es.c- if (p == 0xf2 || p == 0xf3) > -- > kernel/uprobes.c: for (i = 0; i < insn->prefixes.nbytes; i++) { > kernel/uprobes.c- insn_attr_t attr; > kernel/uprobes.c- > kernel/uprobes.c- attr = inat_get_opcode_attribute(insn->prefixes.bytes[i]); > -- > kernel/uprobes.c: for (i = 0; i < insn->prefixes.nbytes; i++) { > kernel/uprobes.c- if (insn->prefixes.bytes[i] == 0x66) > kernel/uprobes.c- return -ENOTSUPP; > kernel/uprobes.c- } > -- > lib/insn-eval.c: for (i = 0; i < insn->prefixes.nbytes; i++) { > lib/insn-eval.c- insn_byte_t p = insn->prefixes.bytes[i]; > lib/insn-eval.c- > lib/insn-eval.c- if (p == 0xf2 || p == 0xf3) > -- > lib/insn-eval.c: for (i = 0; i < insn->prefixes.nbytes; i++) { > lib/insn-eval.c- insn_attr_t attr; > lib/insn-eval.c- > lib/insn-eval.c- attr = inat_get_opcode_attribute(insn->prefixes.bytes[i]); > > I don't see a clear way to fix this. For the loop, we can check the insn.prefixes.bytes[i] == 0 since it is initialized by 0 and 0x0 is not a prefix like this. for (i = 0; insn->prefixes.bytes[i] && i < 4; i++) { ... } Thank you, > > -Kees > > On Mon, Sep 21, 2020 at 09:20:07PM -0700, syzbot wrote: > > syzbot has bisected this issue to: > > > > commit 4b2bd5fec007a4fd3fc82474b9199af25013de4c > > Author: John Stultz <john.stultz@linaro.org> > > Date: Sat Oct 8 00:02:33 2016 +0000 > > > > proc: fix timerslack_ns CAP_SYS_NICE check when adjusting self > > > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1697348d900000 > > start commit: 325d0eab Merge branch 'akpm' (patches from Andrew) > > git tree: upstream > > final oops: https://syzkaller.appspot.com/x/report.txt?x=1597348d900000 > > console output: https://syzkaller.appspot.com/x/log.txt?x=1197348d900000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=b12e84189082991c > > dashboard link: https://syzkaller.appspot.com/bug?extid=9b64b619f10f19d19a7c > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1573a8ad900000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=164ee6c5900000 > > > > Reported-by: syzbot+9b64b619f10f19d19a7c@syzkaller.appspotmail.com > > Fixes: 4b2bd5fec007 ("proc: fix timerslack_ns CAP_SYS_NICE check when adjusting self") > > > > For information about bisection process see: https://goo.gl/tpsmEJ#bisection > > -- > Kees Cook -- Masami Hiramatsu <mhiramat@kernel.org> ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2020-12-02 6:13 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2020-09-20 23:02 UBSAN: array-index-out-of-bounds in arch_uprobe_analyze_insn syzbot 2020-09-21 0:13 ` syzbot 2020-09-22 4:20 ` syzbot 2020-12-02 0:48 ` Kees Cook 2020-12-02 6:12 ` Masami Hiramatsu
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