Re: [Crash-utility] [ANNOUNCE] crash version 7.2.2 is available

Yes, using a different version of GCC/GLIBC can reveal/hide bugs due to slightly different memory layout - I saw this several times. Alex On 2018-05-17 10:17 AM, Dave Anderson wrote: > > ----- Original Message ----- >> Alex, >> >> Just for a sanity check, can you try rebuilding without this 7.2.2 patch: >> >> commit 11eceac4ef54e9bf7d64ce3c96a7454aeb126fd8 >> Author: Dave Anderson <anderson(a)redhat.com&gt; >> Date: Fri Apr 20 14:37:52 2018 -0400 >> >> Fixes to address several gcc-8.0.1 compiler warnings that are generated >> when building with "make warn". The warnings are all false alarm >> messages of type [-Wformat-overflow=], [-Wformat-truncation=] and >> [-Wstringop-truncation]; the affected files are extensions.c, task.c, >> kernel.c, memory.c, remote.c, symbols.c, filesys.c and xen_hyper.c. >> (anderson(a)redhat.com) >> >> It does modify some buffer sizes used by the mount command. >> >> Thanks, >> Dave > It's this, where the read_string() call into buf4 should be shortened to (BUFSIZE/2)-1: > > --- a/filesys.c > +++ b/filesys.c > @@ -1366,10 +1366,10 @@ show_mounts(ulong one_vfsmount, int flags, struct task_context *namespace_contex > long s_dirty; > ulong devp, dirp, sbp, dirty, type, name; > struct list_data list_data, *ld; > - char buf1[BUFSIZE]; > + char buf1[BUFSIZE*2]; > char buf2[BUFSIZE]; > char buf3[BUFSIZE]; > - char buf4[BUFSIZE]; > + char buf4[BUFSIZE/2]; > ulong *dentry_list, *dp, *mntlist; > ulong *vfsmnt; > char *vfsmount_buf, *super_block_buf, *mount_buf; > @@ -1494,8 +1494,8 @@ show_mounts(ulong one_vfsmount, int flags, struct task_context *namespace_contex > KVADDR, &name, sizeof(void *), > "file_system_type name", FAULT_ON_ERROR); > > - if (read_string(name, buf1, BUFSIZE-1)) > - sprintf(buf3, "%-6s ", buf1); > + if (read_string(name, buf4, BUFSIZE-1)) > + sprintf(buf3, "%-6s ", buf4); > else > sprintf(buf3, "unknown "); > > > Dave > > > > > >> >> ----- Original Message ----- >>> Well, stepping in GDB line-by-line I can see that we segfault at #1594 in >>> filesys.c >>> >>> 1588 if (!one_vfsmount) >>> (gdb) >>> 1589 FREEBUF(mntlist); >>> (gdb) >>> 1590 if (VALID_STRUCT(mount)) >>> (gdb) >>> 1593 FREEBUF(vfsmount_buf); >>> (gdb) >>> 1594 FREEBUF(super_block_buf); >>> (gdb) >>> 1595 } >>> (gdb) >>> 0x0000000000000000 in ?? () >>> >>> That is, there is definitely memory corruption somewhere and 'mount' is >>> most >>> probably just a victim. >>> >>> Alex >>> >>> On 2018-05-17 09:36 AM, Alex Sidorenko wrote: >>> >>> >>> crash> mount >>> VFSMOUNT SUPERBLK TYPE DEVNAME DIRNAME >>> ffff88101c916080 ffff88081c837400 rootfs rootfs / >>> >>> Program received signal SIGSEGV, Segmentation fault. >>> 0x0000000000000000 in ?? () >>> (gdb) bt >>> Python Exception <type 'exceptions.ImportError'> No module named >>> gdb.frames: >>> #0 0x0000000000000000 in ?? () >>> #1 0x0000000000000000 in ?? () >>> -- >>> Alex Sidorenko Expert Technologist >>> ERT Linux HPE Pointnext asid(a)hpe.com +1 514-941-8030 Mobile >>> 2344 Boulevard Alfred Nobel, Saint-Laurent, QC, Canada >>> >>> -- >>> Crash-utility mailing list >>> Crash-utility(a)redhat.com >>> https://www.redhat.com/mailman/listinfo/crash-utility >> -- >> Crash-utility mailing list >> Crash-utility(a)redhat.com >> https://www.redhat.com/mailman/listinfo/crash-utility >> > -- > Crash-utility mailing list > Crash-utility(a)redhat.com > https://www.redhat.com/mailman/listinfo/crash-utility > -- Alex Sidorenko Expert Technologist ERT Linux HPE Pointnext asid(a)hpe.com +1 514-941-8030 Mobile 2344 Boulevard Alfred Nobel, Saint-Laurent, QC, Canada