Re: [Crash-utility] [ANNOUNCE] crash version 7.2.2 is available
Hi Alex,
Although I still don't understand why it's only reproducible when crash
is built with certain compilers, I guess it has something to do with how
the local variables are laid out on the function's stack?
Thanks for catching this -- I'll release a 7.2.3 version with the fix
later today.
Dave
----- Original Message -----
----- 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>
> 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 ");
I can reproduce it on a RHEL6 host, but not with new gcc versions.
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
> >
> > --
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>
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