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GNU C Library master sources branch master updated. glibc-2.26.9000-848-g8d81ce0


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http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=8d81ce0c6d6ca923571e8b2bac132929f9a02973

commit 8d81ce0c6d6ca923571e8b2bac132929f9a02973
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Tue Nov 28 09:56:47 2017 -0800

    Properly compute offsets of note descriptor and next note [BZ #22370]
    
    A note header has 3 4-bytes fields, followed by note name and note
    descriptor.  According to gABI, in a note entry, the note name field,
    not note name size, is padded for the note descriptor.  And the note
    descriptor field, not note descriptor size, is padded for the next
    note entry.  Notes are aligned to 4 bytes in 32-bit objects and 8 bytes
    in 64-bit objects.
    
    For all GNU notes, the name is "GNU" which is 4 bytes.  They have the
    same format in the first 16 bytes in both 32-bit and 64-bit objects.
    They differ by note descriptor size and note type.  So far, .note.ABI-tag
    and .note.gnu.build-id notes are always aligned to 4 bytes.  The exsting
    codes compute the note size by aligning the note name size and note
    descriptor size to 4 bytes.  It happens to produce the same value as
    the actual note size by luck since the name size is 4 and offset of the
    note descriptor is 16.  But it will produce the wrong size when note
    alignment is 8 bytes in 64-bit objects.
    
    This patch defines ELF_NOTE_DESC_OFFSET and ELF_NOTE_NEXT_OFFSET to
    properly compute offsets of note descriptor and next note.  It uses
    alignment of PT_NOTE segment to support both 4-byte and 8-byte note
    alignments in 64-bit objects.  To handle PT_NOTE segments with
    incorrect alignment, which may lead to an infinite loop, if segment
    alignment is less than 4, we treate alignment as 4 bytes since some
    note segments have 0 or 1 byte alignment.
    
    	[BZ #22370]
    	* elf/dl-hwcaps.c (ROUND): Removed.
    	(_dl_important_hwcaps): Replace ROUND with ELF_NOTE_DESC_OFFSET
    	and ELF_NOTE_NEXT_OFFSET.
    	* elf/dl-load.c (ROUND): Removed.
    	(open_verify): Replace ROUND with ELF_NOTE_NEXT_OFFSET.
    	* elf/readelflib.c (ROUND): Removed.
    	(process_elf_file): Replace ROUND with ELF_NOTE_NEXT_OFFSET.
    	* include/elf.h [!_ISOMAC]: Include <libc-pointer-arith.h>.
    	[!_ISOMAC] (ELF_NOTE_DESC_OFFSET): New.
    	[!_ISOMAC] (ELF_NOTE_NEXT_OFFSET): Likewise.

diff --git a/ChangeLog b/ChangeLog
index 77092bb..593811d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,17 @@
+2017-11-28  H.J. Lu  <hongjiu.lu@intel.com>
+
+	[BZ #22370]
+	* elf/dl-hwcaps.c (ROUND): Removed.
+	(_dl_important_hwcaps): Replace ROUND with ELF_NOTE_DESC_OFFSET
+	and ELF_NOTE_NEXT_OFFSET.
+	* elf/dl-load.c (ROUND): Removed.
+	(open_verify): Replace ROUND with ELF_NOTE_NEXT_OFFSET.
+	* elf/readelflib.c (ROUND): Removed.
+	(process_elf_file): Replace ROUND with ELF_NOTE_NEXT_OFFSET.
+	* include/elf.h [!_ISOMAC]: Include <libc-pointer-arith.h>.
+	[!_ISOMAC] (ELF_NOTE_DESC_OFFSET): New.
+	[!_ISOMAC] (ELF_NOTE_NEXT_OFFSET): Likewise.
+
 2017-11-28  Joseph Myers  <joseph@codesourcery.com>
 
 	* sysdeps/s390/fpu/s_fmaf.c: Include <libm-alias-float.h>.
diff --git a/elf/dl-hwcaps.c b/elf/dl-hwcaps.c
index 92f2eb4..27ba612 100644
--- a/elf/dl-hwcaps.c
+++ b/elf/dl-hwcaps.c
@@ -67,6 +67,18 @@ _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
 	  {
 	    const ElfW(Addr) start = (phdr[i].p_vaddr
 				      + GLRO(dl_sysinfo_map)->l_addr);
+	    /* NB: Some PT_NOTE segment may have alignment value of 0
+	       or 1.  gABI specifies that PT_NOTE segments should be
+	       aligned to 4 bytes in 32-bit objects and to 8 bytes in
+	       64-bit objects.  As a Linux extension, we also support
+	       4 byte alignment in 64-bit objects.  If p_align is less
+	       than 4, we treate alignment as 4 bytes since some note
+	       segments have 0 or 1 byte alignment.   */
+	    ElfW(Addr) align = phdr[i].p_align;
+	    if (align < 4)
+	      align = 4;
+	    else if (align != 4 && align != 8)
+	      continue;
 	    /* The standard ELF note layout is exactly as the anonymous struct.
 	       The next element is a variable length vendor name of length
 	       VENDORLEN (with a real length rounded to ElfW(Word)), followed
@@ -80,7 +92,6 @@ _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
 	    } *note = (const void *) start;
 	    while ((ElfW(Addr)) (note + 1) - start < phdr[i].p_memsz)
 	      {
-#define ROUND(len) (((len) + sizeof (ElfW(Word)) - 1) & -sizeof (ElfW(Word)))
 		/* The layout of the type 2, vendor "GNU" note is as follows:
 		   .long <Number of capabilities enabled by this note>
 		   .long <Capabilities mask> (as mask >> _DL_FIRST_EXTRA).
@@ -91,17 +102,18 @@ _dl_important_hwcaps (const char *platform, size_t platform_len, size_t *sz,
 		    && !memcmp ((note + 1), "GNU", sizeof "GNU")
 		    && note->datalen > 2 * sizeof (ElfW(Word)) + 2)
 		  {
-		    const ElfW(Word) *p = ((const void *) (note + 1)
-					   + ROUND (sizeof "GNU"));
+		    const ElfW(Word) *p
+		      = ((const void *) note
+			 + ELF_NOTE_DESC_OFFSET (sizeof "GNU", align));
 		    cnt += *p++;
 		    ++p;	/* Skip mask word.  */
 		    dsocaps = (const char *) p; /* Pseudo-string "<b>name"  */
 		    dsocapslen = note->datalen - sizeof *p * 2;
 		    break;
 		  }
-		note = ((const void *) (note + 1)
-			+ ROUND (note->vendorlen) + ROUND (note->datalen));
-#undef ROUND
+		note = ((const void *) note
+			+ ELF_NOTE_NEXT_OFFSET (note->vendorlen,
+						note->datalen, align));
 	      }
 	    if (dsocaps != NULL)
 	      break;
diff --git a/elf/dl-load.c b/elf/dl-load.c
index 1220183..10d859b 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -1683,6 +1683,18 @@ open_verify (const char *name, int fd,
 	if (ph->p_type == PT_NOTE && ph->p_filesz >= 32 && ph->p_align >= 4)
 	  {
 	    ElfW(Addr) size = ph->p_filesz;
+	    /* NB: Some PT_NOTE segment may have alignment value of 0
+	       or 1.  gABI specifies that PT_NOTE segments should be
+	       aligned to 4 bytes in 32-bit objects and to 8 bytes in
+	       64-bit objects.  As a Linux extension, we also support
+	       4 byte alignment in 64-bit objects.  If p_align is less
+	       than 4, we treate alignment as 4 bytes since some note
+	       segments have 0 or 1 byte alignment.   */
+	    ElfW(Addr) align = ph->p_align;
+	    if (align < 4)
+	      align = 4;
+	    else if (align != 4 && align != 8)
+	      continue;
 
 	    if (ph->p_offset + size <= (size_t) fbp->len)
 	      abi_note = (void *) (fbp->buf + ph->p_offset);
@@ -1696,10 +1708,9 @@ open_verify (const char *name, int fd,
 
 	    while (memcmp (abi_note, &expected_note, sizeof (expected_note)))
 	      {
-#define ROUND(len) (((len) + sizeof (ElfW(Word)) - 1) & -sizeof (ElfW(Word)))
-		ElfW(Addr) note_size = 3 * sizeof (ElfW(Word))
-				       + ROUND (abi_note[0])
-				       + ROUND (abi_note[1]);
+		ElfW(Addr) note_size
+		  = ELF_NOTE_NEXT_OFFSET (abi_note[0], abi_note[1],
+					  align);
 
 		if (size - 32 < note_size)
 		  {
diff --git a/elf/readelflib.c b/elf/readelflib.c
index 9ad56dc..3a303ff 100644
--- a/elf/readelflib.c
+++ b/elf/readelflib.c
@@ -131,15 +131,26 @@ process_elf_file (const char *file_name, const char *lib, int *flag,
 	      ElfW(Word) *abi_note = (ElfW(Word) *) (file_contents
 						     + segment->p_offset);
 	      ElfW(Addr) size = segment->p_filesz;
+	      /* NB: Some PT_NOTE segment may have alignment value of 0
+		 or 1.  gABI specifies that PT_NOTE segments should be
+		 aligned to 4 bytes in 32-bit objects and to 8 bytes in
+		 64-bit objects.  As a Linux extension, we also support
+		 4 byte alignment in 64-bit objects.  If p_align is less
+		 than 4, we treate alignment as 4 bytes since some note
+		 segments have 0 or 1 byte alignment.   */
+	      ElfW(Addr) align = segment->p_align;
+	      if (align < 4)
+		align = 4;
+	      else if (align != 4 && align != 8)
+		continue;
 
 	      while (abi_note [0] != 4 || abi_note [1] != 16
 		     || abi_note [2] != 1
 		     || memcmp (abi_note + 3, "GNU", 4) != 0)
 		{
-#define ROUND(len) (((len) + sizeof (ElfW(Word)) - 1) & -sizeof (ElfW(Word)))
-		  ElfW(Addr) note_size = 3 * sizeof (ElfW(Word))
-					 + ROUND (abi_note[0])
-					 + ROUND (abi_note[1]);
+		  ElfW(Addr) note_size
+		    = ELF_NOTE_NEXT_OFFSET (abi_note[0], abi_note[1],
+					    align);
 
 		  if (size - 32 < note_size || note_size == 0)
 		    {
diff --git a/include/elf.h b/include/elf.h
index f06a33f..ab76aaf 100644
--- a/include/elf.h
+++ b/include/elf.h
@@ -1,7 +1,19 @@
 #ifndef _ELF_H
 #include <elf/elf.h>
 
-# ifndef _ISOMAC
+#ifndef _ISOMAC
+
+# include <libc-pointer-arith.h>
+
+/* Compute the offset of the note descriptor from size of note entry's
+   owner string and note alignment.  */
+# define ELF_NOTE_DESC_OFFSET(namesz, align) \
+  ALIGN_UP (sizeof (ElfW(Nhdr)) + (namesz), (align))
+
+/* Compute the offset of the next note entry from size of note entry's
+   owner string, size of the note descriptor and note alignment.  */
+# define ELF_NOTE_NEXT_OFFSET(namesz, descsz, align) \
+  ALIGN_UP (ELF_NOTE_DESC_OFFSET ((namesz), (align)) + (descsz), (align))
 
 /* Some information which is not meant for the public and therefore not
    in <elf.h>.  */
@@ -13,5 +25,5 @@
    (DF_1_NOW | DF_1_NODELETE | DF_1_INITFIRST | DF_1_NOOPEN \
     | DF_1_ORIGIN | DF_1_NODEFLIB)
 
-# endif /* !_ISOMAC */
+#endif /* !_ISOMAC */
 #endif /* elf.h */

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog        |   14 ++++++++++++++
 elf/dl-hwcaps.c  |   24 ++++++++++++++++++------
 elf/dl-load.c    |   19 +++++++++++++++----
 elf/readelflib.c |   19 +++++++++++++++----
 include/elf.h    |   16 ++++++++++++++--
 5 files changed, 76 insertions(+), 16 deletions(-)


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