On Wed, Dec 3, 2014 at 3:39 PM, Andrey Ryabinin <a.ryabi...@samsung.com> wrote: > On 12/03/2014 12:04 PM, Dmitry Vyukov wrote: >> Hi, >> >> I am working on AddressSanitizer, a fast memory error detector for kernel: >> https://code.google.com/p/address-sanitizer/wiki/AddressSanitizerForKernel >> >> Here is a bug report that I've got while running trinity: >> >> ================================================================== >> BUG: AddressSanitizer: out of bounds access in >> __do_proc_doulongvec_minmax+0x8a0/0x9a0 at addr ffffffff83980960 >> Read of size 8 by task trinity-c14/6919 >> Out-of-bounds access to the global variable 'zero' >> [ffffffff83980960-ffffffff83980964) defined at ipc/ipc_sysctl.c:158 > > This line seems incorrect. Judging from the backtrace below variable 'zero' is > defined in kernel/sysctl.c:123 > > >> >> CPU: 1 PID: 6919 Comm: trinity-c14 Not tainted 3.18.0-rc1+ #50 >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 >> 0000000000000001 ffff8800b68cf418 ffffffff82c2d3ae 0000000000000000 >> ffff8800b68cf4c0 ffff8800b68cf4a8 ffffffff813eaa81 ffffffff0000000c >> ffff88010b003600 ffff8800b68cf479 0000000000000296 0000000000000000 >> Call Trace: >> [<ffffffff813ead71>] __asan_report_load8_noabort+0x51/0x70 >> mm/kasan/report.c:248 >> [<ffffffff810cc3e0>] __do_proc_doulongvec_minmax+0x8a0/0x9a0 >> kernel/sysctl.c:2284 >> [< inlined >] proc_doulongvec_minmax+0x50/0x80 >> do_proc_doulongvec_minmax kernel/sysctl.c:2322 >> [<ffffffff810cc530>] proc_doulongvec_minmax+0x50/0x80 kernel/sysctl.c:2345 >> [<ffffffff813c9e5a>] hugetlb_sysctl_handler_common+0x12a/0x3c0 >> mm/hugetlb.c:2270 >> [<ffffffff813cb45c>] hugetlb_mempolicy_sysctl_handler+0x1c/0x20 >> mm/hugetlb.c:2293 >> [<ffffffff8153e6e9>] proc_sys_call_handler+0x179/0x1f0 >> fs/proc/proc_sysctl.c:506 >> [<ffffffff8153e76f>] proc_sys_write+0xf/0x20 fs/proc/proc_sysctl.c:524 >> [<ffffffff813f1563>] __kernel_write+0x123/0x440 fs/read_write.c:502 >> [<ffffffff8147ebaa>] write_pipe_buf+0x14a/0x1d0 fs/splice.c:1074 >> [< inlined >] __splice_from_pipe+0x22e/0x6f0 >> splice_from_pipe_feed fs/splice.c:769 >> [<ffffffff8147dbde>] __splice_from_pipe+0x22e/0x6f0 fs/splice.c:886 >> [<ffffffff81483211>] splice_from_pipe+0xc1/0x110 fs/splice.c:921 >> [<ffffffff81483298>] default_file_splice_write+0x18/0x50 fs/splice.c:1086 >> [< inlined >] direct_splice_actor+0x104/0x1c0 do_splice_from >> fs/splice.c:1128 >> [<ffffffff8147cfc4>] direct_splice_actor+0x104/0x1c0 fs/splice.c:1284 >> [<ffffffff8147e5ba>] splice_direct_to_actor+0x24a/0x6f0 fs/splice.c:1237 >> [<ffffffff81483424>] do_splice_direct+0x154/0x270 fs/splice.c:1327 >> [<ffffffff813f3bfb>] do_sendfile+0x5fb/0x1260 fs/read_write.c:1266 >> [< inlined >] SyS_sendfile64+0xfa/0x100 SYSC_sendfile64 >> fs/read_write.c:1327 >> [<ffffffff813f6bea>] SyS_sendfile64+0xfa/0x100 fs/read_write.c:1313 >> [<ffffffff82c464f9>] ia32_do_call+0x13/0x13 arch/x86/ia32/ia32entry.S:444 >> Memory state around the buggy address: >> ffffffff83980680: 04 f8 f8 f8 f8 f8 f8 f8 02 f8 f8 f8 f8 f8 f8 f8 >> ffffffff83980700: 00 f8 f8 f8 f8 f8 f8 f8 00 f8 f8 f8 f8 f8 f8 f8 >> ffffffff83980780: 00 00 00 00 00 00 00 00 f8 f8 f8 f8 00 00 00 00 >> ffffffff83980800: 00 00 00 00 00 00 00 00 f8 f8 f8 f8 04 f8 f8 f8 >> ffffffff83980880: f8 f8 f8 f8 04 f8 f8 f8 f8 f8 f8 f8 04 f8 f8 f8 >>> ffffffff83980900: f8 f8 f8 f8 04 f8 f8 f8 f8 f8 f8 f8 04 f8 f8 f8 >> ^ >> ffffffff83980980: f8 f8 f8 f8 00 00 00 00 f8 f8 f8 f8 00 00 00 00 >> ffffffff83980a00: 02 f8 f8 f8 f8 f8 f8 f8 00 00 00 00 00 00 00 00 >> ffffffff83980a80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >> ffffffff83980b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >> ffffffff83980b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >> ================================================================== >> >> The core creates ctl_table as: >> >> static int zero; >> static int one = 1; >> static int int_max = INT_MAX; >> static struct ctl_table ipc_kern_table[] = { >> { >> ... >> { >> .procname = "shm_rmid_forced", >> .data = &init_ipc_ns.shm_rmid_forced, >> .maxlen = sizeof(init_ipc_ns.shm_rmid_forced), >> .mode = 0644, >> .proc_handler = proc_ipc_dointvec_minmax_orphans, >> .extra1 = &zero, >> .extra2 = &one, >> }, >> >> But later extra1/2 are casted to *unsigned long**: >> >> static int __do_proc_doulongvec_minmax(void *data, struct ctl_table >> *table, int write, ... >> { >> ... >> min = (unsigned long *) table->extra1; >> max = (unsigned long *) table->extra2; >> >> This leads to bogus bounds check for the sysctl value. >> >> The bug is added in commit: >> >> commit 9eefe520c814f6f62c5d36a2ddcd3fb99dfdb30e >> Author: Nadia Derbey <nadia.der...@bull.net> >> Date: Fri Jul 25 01:48:08 2008 -0700 >> >> Later zero and one were used in a bunch of other ctl_table's. >> > > I think you are blaming wrong commit. This bug was introduced by > ed4d4902ebdd7ca8b5a51daaf6bebf4b172895cc ("mm, hugetlb: remove hugetlb_zero > and hugetlb_infinity") > > We have two options to fix this. Reintroduce back hugetlb_zero or make 'zero' > unsigned long instead. > I would prefer the latter, changing type to 'unsigned long' shouldn't harm > any other users of this variable. >
ipc/ipc_sysctl.c also contains zero, one and int_max variables that are used in a similar way: static int zero; static int one = 1; static int int_max = INT_MAX; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
