Bug 1190454 - stpcpy (mempcpy) segfaults on CPUs without SSE2
Summary: stpcpy (mempcpy) segfaults on CPUs without SSE2
Alias: None
Product: Fedora
Classification: Fedora
Component: glibc
Version: 22
Hardware: Unspecified
OS: Unspecified
Target Milestone: ---
Assignee: Carlos O'Donell
QA Contact: Fedora Extras Quality Assurance
Depends On:
TreeView+ depends on / blocked
Reported: 2015-02-08 03:58 UTC by Bruno Wolff III
Modified: 2017-10-30 15:35 UTC (History)
17 users (show)

Fixed In Version: glibc-2.21-3.fc22
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2016-02-05 16:08:17 UTC
Type: Bug

Attachments (Terms of Use)

System ID Private Priority Status Summary Last Updated
Sourceware 17949 0 None None None Never

Description Bruno Wolff III 2015-02-08 03:58:44 UTC
Description of problem:
ls -l segfaults

This machine has 2 AMD MP processors and those have some differences in instruction set from Intel's i686 machines and that could potentially be related to the problem.

Version-Release number of selected component (if applicable):

How reproducible:
Everytime I run ls -l

Additional info:
gdb /usr/bin/ls
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Reading symbols from /usr/bin/ls...Reading symbols from /usr/bin/ls...(no debugging symbols found)...done.
(no debugging symbols found)...done.
Missing separate debuginfos, use: debuginfo-install coreutils-8.23-6.fc22.i686
(gdb) run -l
Starting program: /usr/bin/ls -l
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/libthread_db.so.1".
total 524

Program received signal SIGSEGV, Segmentation fault.
0xb7dc795c in __stpcpy_ia32 () from /lib/libc.so.6
(gdb) where
#0  0xb7dc795c in __stpcpy_ia32 () from /lib/libc.so.6
#1  0x0804e88a in align_nstrftime.constprop ()
#2  0x0804fa9a in print_long_format ()
#3  0x0805036c in print_current_files ()
#4  0x0804b76c in main ()

Comment 1 Pádraig Brady 2015-02-08 15:47:32 UTC
It's conceivable though unlikely than a tm_mon outside the range 0..11 is being returned on your platform. This defensive patch would protect against that:

diff --git a/src/ls.c b/src/ls.c
index cb9d3d6..4698520 100644
--- a/src/ls.c
+++ b/src/ls.c
@@ -3665,7 +3665,8 @@ align_nstrftime (char *buf, size_t size, char const *fmt, 
      the replacement is not done.  A malloc here slows ls down by 2%  */
   char rpl_fmt[sizeof (abmon[0]) + 100];
   const char *pb;
-  if (required_mon_width && (pb = strstr (fmt, "%b")))
+  if (required_mon_width && (pb = strstr (fmt, "%b"))
+      && 0 <= tm->tm_mon && tm->tm_mon <= 11)
       if (strlen (fmt) < (sizeof (rpl_fmt) - sizeof (abmon[0]) + 2))

If that doesn't help, it does suggest an issue with the stpcpy
implementation in libc. In either case running through a debugger would be informative:

  wget ftp://ftp.gnu.org/pub/gnu/coreutils/coreutils-8.23.tar.xz
  tar -xf coreutils-8.23.tar.xz
  cd coreutils-8.23
  patch p1  #paste the above
  ./configure --quiet && make CFLAGS=-ggdb -j3
  gdb -tui -args src/ls -l
  (gdb) b align_nstrftime
  (gdb) p tm->tm_mon

Comment 2 Bruno Wolff III 2015-02-09 23:21:57 UTC
This doesn't seem to have gone as expected. Some source gets listed after starting, but commands don't seem to be working as expected.

   │1243    {                                                                                                                                         │
   │1244      int i;                                                                                                                                  │
   │1245      struct pending *thispend;                                                                                                               │
   │1246      int n_files;                                                                                                                            │
   │1247                                                                                                                                              │
   │1248      /* The signals that are trapped, and the number of such signals.  */                                                                    │
   │1249      static int const sig[] =                                                                                                                │
   │1250        {                                                                                                                                     │
   │1251          /* This one is handled specially.  */                                                                                               │
   │1252          SIGTSTP,                                                                                                                            │
   │1253                                                                                                                                              │
   │1254          /* The usual suspects.  */                                                                                                          │
   │1255          SIGALRM, SIGHUP, SIGINT, SIGPIPE, SIGQUIT, SIGTERM,                                                                                 │
   │1256    #ifdef SIGPOLL                                                                                                                            │
   │1257          SIGPOLL,                                                                                                                            │
   │1258    #endif                                                                                                                                    │
   │1259    #ifdef SIGPROF                                                                                                                            │
   │1260          SIGPROF,                                                                                                                            │
   │1261    #endif                                                                                                                                    │
   │1262    #ifdef SIGVTALRM                                                                                                                          │
   │1263          SIGVTALRM,                                                                                                                          │
   │1264    #endif                                                                                                                                    │
   │1265    #ifdef SIGXCPU                                                                                                                            │
   │1266          SIGXCPU,                                                                                                                            │
   │1267    #endif                                                                                                                                    │
   │1268    #ifdef SIGXFSZ                                                                                                                            │
   │1269          SIGXFSZ,                                             

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Reading symbols from src/ls...done.
(gdb) b	align_nstrftime
Breakpoint 1 at	0x804f1df: file	src/ls.c, line 3666.
(gdb) p	tm->tm_mon
No symbol "tm" in current context.
(gdb) c
The program is not being run.

Comment 3 Bruno Wolff III 2015-02-09 23:24:30 UTC
src/ls -l works normally, while the system ls still segfaults.

Comment 4 Bruno Wolff III 2015-02-09 23:29:15 UTC
I added a run step that might have been missing.
The month value looked OK for a few iterations.

(gdb) p tm->tm_mon
$2 = 6
(gdb) c

Breakpoint 1, align_nstrftime (buf=0xbfffd6f5 "\001-.  1 ", size=1001, fmt=0x805c714 "%b %e  %Y", tm=0xb7f1ebc0 <_tmbuf>, __utc=0, __ns=0)
    at src/ls.c:3666

Comment 5 Pádraig Brady 2015-02-10 01:16:46 UTC
oops sorry, yes I missed the run step.
It's interesting/annoying that only the system version segfaults.
Do you have ls aliased to add any time style options etc?
Perhaps you have a TIME_STYLE env variable that's not passed through the debugger, in which case you'd need a --time-style to simulate for the command passed to the debugger.

Comment 6 Pádraig Brady 2015-02-10 01:31:14 UTC
Can you reproduce in the debugger for the system version?

# yum install coreutils-debuginfo
$ gdb -tui -args /usr/bin/ls -l
(gdb) b align_nstrftime
(gdb) r
(gdb) p tm->tm_mon
(gdb) c

If not reproducible under the debugger, perhaps the
TZ env var is different under the debugger and your shell?

Comment 7 Allan 2015-02-10 03:54:20 UTC
We had the same issue in Arch Linux with glibc-2.21. This is our proposed fix for glibc:

Comment 8 Bruno Wolff III 2015-02-10 04:10:26 UTC
This might be moot now given the above comment, but for completeness:

Missing separate debuginfos, use: debuginfo-install libacl-2.2.52-7.fc22.i686 libattr-2.4.47-9.fc22.i686 libcap-2.24-7.fc22.i686 libselinux-2.3-6.fc22.
i686 pcre-8.36-3.fc22.i686 xz-libs-5.2.0-2.fc22.i686
(gdb) p	tm->tm_mon
$1 = 9
(gdb) c

Program	received signal	SIGSEGV, Segmentation fault.
0xb7dc794c in __stpcpy_ia32 () from /lib/libc.so.6

Comment 9 Pádraig Brady 2015-02-10 12:36:02 UTC
Thanks guys! That confirms the problem is within stpcpy and is mostly likely the issue that Allan identified. Bruno, I am confused as to why your built version didn't also hit the issue. If it was using the gnulib replacement rather than the glibc version it would explain things, but I don't know why it would use the replacement. It's not using the replacement if you see HAVE_STPCPY in the output of `grep STPCPY lib/config.h`. It would be useful to confirm that from the directory where you built coreutils as instructed in comment #1.

Comment 10 Evangelos Foutras 2015-02-10 12:46:28 UTC
In my testing 'ls -l' wouldn't segfault when ls.c was built with -O0, only when using -O1 or higher optimization levels. This would explain why Bruno's build worked fine.

Comment 11 Felix Miata 2015-02-12 18:15:22 UTC
Any of the ls options produce segfault on my Socket A systems, including the default aliases.

Comment 12 Bruno Wolff III 2015-02-14 21:15:01 UTC
ls -l seems to be working again.

Comment 13 Pádraig Brady 2015-02-14 22:24:13 UTC
Thanks for the feedback Bruno.

Yep, rawhide 2.21.90-2 uses glibc master branch at commit ebf27d1,
which includes the pertinent commit (132a132).


Comment 14 Felix Miata 2015-02-14 22:30:42 UTC
(In reply to Bruno Wolff III from comment #12)
> ls -l seems to be working again.

Running what, a fresh installation, or an upgrade? Upgrading F22 on Socket A host kt880 didn't install a newer coreutils or stop the optioned ls segfaulting: 

Comment 15 Pádraig Brady 2015-02-15 12:27:03 UTC
Right, F22 is not updated yet. Note the fix is on the 2.21 branch upstream:

Comment 16 Carlos O'Donell 2015-02-17 15:31:14 UTC
(In reply to Pádraig Brady from comment #15)
> Right, F22 is not updated yet. Note the fix is on the 2.21 branch upstream:
> https://sourceware.org/git/?p=glibc.git;a=shortlog;h=refs/heads/release/2.21/
> master

F22 has the fix for this bug. The glibc-2.21-1 should not fail. Just to make sure I've bumped the NVR and kicked off a rebuild to redo the testing. Thus glibc-2.21-2.fc22 should absolutely have the fix for this segfault problem, otherwise it's another problem and we need someone to provide some SOS info about the failure e.g. backtrace.

Upcoming build:

Comment 17 Pádraig Brady 2015-02-17 17:03:01 UTC
The patch wasn't applied to the f22 build due to bugs in rpm.
These are tracked at bug #1193603

Carlos is working around the issue in a further build.

Comment 18 Carlos O'Donell 2015-02-18 03:32:18 UTC
Fixed in glibc-2.21-3.fc22.

Comment 19 Carlos O'Donell 2015-02-18 03:32:53 UTC
Final build in progress:

Comment 20 Florian Weimer 2016-02-05 16:08:17 UTC
This was fixed in Fedora 22.

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