Fix BZ 20419. 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.
This commit is contained in:
Paul Pluzhnikov
parent
b289cd9db8
commit
0065aaaaae
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@ -1,3 +1,11 @@
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2018-05-05 Paul Pluzhnikov <ppluzhnikov@google.com>
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[BZ #20419]
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* elf/dl-load.c (open_verify): Fix stack overflow.
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* elf/Makefile (tst-big-note): New test.
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* elf/tst-big-note-lib.S: New.
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* elf/tst-big-note.c: New.
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2018-05-04 Joseph Myers <joseph@codesourcery.com>
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* scripts/abilist.awk: Ignore absolute symbols.
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@ -186,7 +186,7 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \
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tst-tlsalign tst-tlsalign-extern tst-nodelete-opened \
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tst-nodelete2 tst-audit11 tst-audit12 tst-dlsym-error tst-noload \
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tst-latepthread tst-tls-manydynamic tst-nodelete-dlclose \
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tst-debug1 tst-main1 tst-absolute-sym
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tst-debug1 tst-main1 tst-absolute-sym tst-big-note
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# reldep9
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tests-internal += loadtest unload unload2 circleload1 \
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neededtest neededtest2 neededtest3 neededtest4 \
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@ -272,7 +272,9 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
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tst-audit12mod1 tst-audit12mod2 tst-audit12mod3 tst-auditmod12 \
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tst-latepthreadmod $(tst-tls-many-dynamic-modules) \
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tst-nodelete-dlclose-dso tst-nodelete-dlclose-plugin \
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tst-main1mod tst-libc_dlvsym-dso tst-absolute-sym-lib
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tst-main1mod tst-libc_dlvsym-dso tst-absolute-sym-lib \
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tst-big-note-lib
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ifeq (yes,$(have-mtls-dialect-gnu2))
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tests += tst-gnu2-tls1
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modules-names += tst-gnu2-tls1mod
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@ -1450,3 +1452,5 @@ $(objpfx)tst-libc_dlvsym-static: $(common-objpfx)dlfcn/libdl.a
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tst-libc_dlvsym-static-ENV = \
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LD_LIBRARY_PATH=$(objpfx):$(common-objpfx):$(common-objpfx)dlfcn
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$(objpfx)tst-libc_dlvsym-static.out: $(objpfx)tst-libc_dlvsym-dso.so
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$(objpfx)tst-big-note: $(objpfx)tst-big-note-lib.so
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@ -1462,6 +1462,7 @@ open_verify (const char *name, int fd,
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ElfW(Ehdr) *ehdr;
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ElfW(Phdr) *phdr, *ph;
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ElfW(Word) *abi_note;
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ElfW(Word) *abi_note_malloced = NULL;
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unsigned int osversion;
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size_t maplength;
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@ -1633,10 +1634,25 @@ open_verify (const char *name, int fd,
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abi_note = (void *) (fbp->buf + ph->p_offset);
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else
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{
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abi_note = alloca (size);
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/* Note: __libc_use_alloca is not usable here, because
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thread info may not have been set up yet. */
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if (size < __MAX_ALLOCA_CUTOFF)
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abi_note = alloca (size);
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else
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{
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/* There could be multiple PT_NOTEs. */
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abi_note_malloced = realloc (abi_note_malloced, size);
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if (abi_note_malloced == NULL)
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goto read_error;
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abi_note = abi_note_malloced;
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}
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__lseek (fd, ph->p_offset, SEEK_SET);
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if (__libc_read (fd, (void *) abi_note, size) != size)
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goto read_error;
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{
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free (abi_note_malloced);
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goto read_error;
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}
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}
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while (memcmp (abi_note, &expected_note, sizeof (expected_note)))
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@ -1671,6 +1687,7 @@ open_verify (const char *name, int fd,
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break;
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}
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free (abi_note_malloced);
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}
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return fd;
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@ -0,0 +1,26 @@
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/* Bug 20419: test for stack overflow in elf/dl-load.c open_verify()
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Copyright (C) 2018 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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/* This creates a .so with 8MiB PT_NOTE segment.
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On a typical Linux system with 8MiB "ulimit -s", that was enough
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to trigger stack overflow in open_verify. */
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.pushsection .note.big,"a"
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.balign 4
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.fill 8*1024*1024, 1, 0
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.popsection
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@ -0,0 +1,26 @@
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/* Bug 20419: test for stack overflow in elf/dl-load.c open_verify()
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Copyright (C) 2018 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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/* This file must be run from within a directory called "elf". */
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int main (int argc, char *argv[])
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{
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/* Nothing to do here: merely linking against tst-big-note-lib.so triggers
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the bug. */
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return 0;
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}
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