* [2.27 COMMITTED] Fix stack overflow with huge PT_NOTE segment [BZ #20419]
@ 2018-01-01 0:00 Dmitry V. Levin
0 siblings, 0 replies; only message in thread
From: Dmitry V. Levin @ 2018-01-01 0:00 UTC (permalink / raw)
To: libc-stable
From: Paul Pluzhnikov <ppluzhnikov@google.com>
A PT_NOTE in a binary could be arbitratily large, so using alloca
for it may cause stack overflow. If the note is larger than
__MAX_ALLOCA_CUTOFF, use dynamically allocated memory to read it in.
2018-05-05 Paul Pluzhnikov <ppluzhnikov@google.com>
[BZ #20419]
* elf/dl-load.c (open_verify): Fix stack overflow.
* elf/Makefile (tst-big-note): New test.
* elf/tst-big-note-lib.S: New.
* elf/tst-big-note.c: New.
(cherry picked from commit 0065aaaaae51cd60210ec3a7e13dddd8e01ffe2c)
---
ChangeLog | 8 ++++++++
elf/Makefile | 8 ++++++--
elf/dl-load.c | 21 +++++++++++++++++++--
elf/tst-big-note-lib.S | 26 ++++++++++++++++++++++++++
elf/tst-big-note.c | 26 ++++++++++++++++++++++++++
5 files changed, 85 insertions(+), 4 deletions(-)
create mode 100644 elf/tst-big-note-lib.S
create mode 100644 elf/tst-big-note.c
diff --git a/ChangeLog b/ChangeLog
index ca6b3ea..14063a1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2018-05-05 Paul Pluzhnikov <ppluzhnikov@google.com>
+
+ [BZ #20419]
+ * elf/dl-load.c (open_verify): Fix stack overflow.
+ * elf/Makefile (tst-big-note): New test.
+ * elf/tst-big-note-lib.S: New.
+ * elf/tst-big-note.c: New.
+
2018-05-04 Stefan Liebler <stli@linux.vnet.ibm.com>
[BZ #23137]
diff --git a/elf/Makefile b/elf/Makefile
index 2a432d8..2d8fe88 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -187,7 +187,7 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \
tst-tlsalign tst-tlsalign-extern tst-nodelete-opened \
tst-nodelete2 tst-audit11 tst-audit12 tst-dlsym-error tst-noload \
tst-latepthread tst-tls-manydynamic tst-nodelete-dlclose \
- tst-debug1 tst-main1
+ tst-debug1 tst-main1 tst-big-note
# reldep9
tests-internal += loadtest unload unload2 circleload1 \
neededtest neededtest2 neededtest3 neededtest4 \
@@ -272,7 +272,9 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
tst-audit12mod1 tst-audit12mod2 tst-audit12mod3 tst-auditmod12 \
tst-latepthreadmod $(tst-tls-many-dynamic-modules) \
tst-nodelete-dlclose-dso tst-nodelete-dlclose-plugin \
- tst-main1mod tst-libc_dlvsym-dso
+ tst-main1mod tst-libc_dlvsym-dso \
+ tst-big-note-lib
+
ifeq (yes,$(have-mtls-dialect-gnu2))
tests += tst-gnu2-tls1
modules-names += tst-gnu2-tls1mod
@@ -1446,3 +1448,5 @@ $(objpfx)tst-libc_dlvsym-static: $(common-objpfx)dlfcn/libdl.a
tst-libc_dlvsym-static-ENV = \
LD_LIBRARY_PATH=$(objpfx):$(common-objpfx):$(common-objpfx)dlfcn
$(objpfx)tst-libc_dlvsym-static.out: $(objpfx)tst-libc_dlvsym-dso.so
+
+$(objpfx)tst-big-note: $(objpfx)tst-big-note-lib.so
diff --git a/elf/dl-load.c b/elf/dl-load.c
index 7554a99..f038e29 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -1469,6 +1469,7 @@ open_verify (const char *name, int fd,
ElfW(Ehdr) *ehdr;
ElfW(Phdr) *phdr, *ph;
ElfW(Word) *abi_note;
+ ElfW(Word) *abi_note_malloced = NULL;
unsigned int osversion;
size_t maplength;
@@ -1640,10 +1641,25 @@ open_verify (const char *name, int fd,
abi_note = (void *) (fbp->buf + ph->p_offset);
else
{
- abi_note = alloca (size);
+ /* Note: __libc_use_alloca is not usable here, because
+ thread info may not have been set up yet. */
+ if (size < __MAX_ALLOCA_CUTOFF)
+ abi_note = alloca (size);
+ else
+ {
+ /* There could be multiple PT_NOTEs. */
+ abi_note_malloced = realloc (abi_note_malloced, size);
+ if (abi_note_malloced == NULL)
+ goto read_error;
+
+ abi_note = abi_note_malloced;
+ }
__lseek (fd, ph->p_offset, SEEK_SET);
if (__libc_read (fd, (void *) abi_note, size) != size)
- goto read_error;
+ {
+ free (abi_note_malloced);
+ goto read_error;
+ }
}
while (memcmp (abi_note, &expected_note, sizeof (expected_note)))
@@ -1678,6 +1694,7 @@ open_verify (const char *name, int fd,
break;
}
+ free (abi_note_malloced);
}
return fd;
diff --git a/elf/tst-big-note-lib.S b/elf/tst-big-note-lib.S
new file mode 100644
index 0000000..6b514a0
--- /dev/null
+++ b/elf/tst-big-note-lib.S
@@ -0,0 +1,26 @@
+/* Bug 20419: test for stack overflow in elf/dl-load.c open_verify()
+ Copyright (C) 2018 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+/* This creates a .so with 8MiB PT_NOTE segment.
+ On a typical Linux system with 8MiB "ulimit -s", that was enough
+ to trigger stack overflow in open_verify. */
+
+.pushsection .note.big,"a"
+.balign 4
+.fill 8*1024*1024, 1, 0
+.popsection
diff --git a/elf/tst-big-note.c b/elf/tst-big-note.c
new file mode 100644
index 0000000..fcd2b0e
--- /dev/null
+++ b/elf/tst-big-note.c
@@ -0,0 +1,26 @@
+/* Bug 20419: test for stack overflow in elf/dl-load.c open_verify()
+ Copyright (C) 2018 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+/* This file must be run from within a directory called "elf". */
+
+int main (int argc, char *argv[])
+{
+ /* Nothing to do here: merely linking against tst-big-note-lib.so triggers
+ the bug. */
+ return 0;
+}
--
ldv
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2018-01-01 0:00 [2.27 COMMITTED] Fix stack overflow with huge PT_NOTE segment [BZ #20419] Dmitry V. Levin
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