GNU C Library master sources branch master updated. glibc-2.26.9000-816-gc45d78a

[azanella at sourceware dot org]

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http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=c45d78aac47db08bc8ea7641c5330cccaecd3ddb

commit c45d78aac47db08bc8ea7641c5330cccaecd3ddb
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Wed Nov 22 18:02:20 2017 -0200

    posix: Fix generic p{read,write}v buffer allocation (BZ#22457)
    
    As described in BZ#22457 an interpose malloc can free an invalid
    pointer for fallback preadv implementation.  Fortunately this is
    just and issue on microblaze-linux-gnu running kernels older than
    3.15.  This patch fixes it by calling mmap/unmap instead of
    posix_memalign/ free.
    
    Checked on microblaze-linux-gnu check with run-built-tests=no and
    by using the sysdeps/posix implementation on x86_64-linux-gnu (just
    for sanity test where it shown no regression).
    
    	[BZ #22457]
    	* sysdeps/posix/preadv_common.c (PREADV): Use mmap/munmap instead of
    	posix_memalign/free.
    	* sysdeps/posix/pwritev_common.c (PWRITEV): Likewise.

diff --git a/ChangeLog b/ChangeLog
index e60983a..6791c51 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2017-11-24  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
+
+	[BZ #22457]
+	* sysdeps/posix/preadv_common.c (PREADV): Use mmap/munmap instead of
+	posix_memalign/free.
+	* sysdeps/posix/pwritev_common.c (PWRITEV): Likewise.
+
 2017-11-22  Mike FABIAN  <mfabian@redhat.com>
 
 	[BZ #22469]
diff --git a/sysdeps/posix/preadv_common.c b/sysdeps/posix/preadv_common.c
index 37efdc0..76cf261 100644
--- a/sysdeps/posix/preadv_common.c
+++ b/sysdeps/posix/preadv_common.c
@@ -24,6 +24,7 @@
 #include <malloc.h>
 
 #include <ldsodefs.h>
+#include <libc-pointer-arith.h>
 
 /* Read data from file descriptor FD at the given position OFFSET
    without change the file pointer, and put the result in the buffers
@@ -54,8 +55,9 @@ PREADV (int fd, const struct iovec *vector, int count, OFF_T offset)
      but 1. it is system specific (not meant in generic implementation), and
      2. it would make the implementation more complex, and 3. it will require
      another syscall (fcntl).  */
-  void *buffer = NULL;
-  if (__posix_memalign (&buffer, GLRO(dl_pagesize), bytes) != 0)
+  void *buffer = __mmap (NULL, bytes, PROT_READ | PROT_WRITE,
+		         MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+  if (__glibc_unlikely (buffer == MAP_FAILED))
     return -1;
 
   ssize_t bytes_read = PREAD (fd, buffer, bytes, offset);
@@ -78,6 +80,6 @@ PREADV (int fd, const struct iovec *vector, int count, OFF_T offset)
     }
 
 end:
-  free (buffer);
+  __munmap (buffer, bytes);
   return bytes_read;
 }
diff --git a/sysdeps/posix/pwritev_common.c b/sysdeps/posix/pwritev_common.c
index 0383065..3528fd8 100644
--- a/sysdeps/posix/pwritev_common.c
+++ b/sysdeps/posix/pwritev_common.c
@@ -24,6 +24,7 @@
 #include <malloc.h>
 
 #include <ldsodefs.h>
+#include <libc-pointer-arith.h>
 
 /* Write data pointed by the buffers described by IOVEC, which is a
    vector of COUNT 'struct iovec's, to file descriptor FD at the given
@@ -54,8 +55,9 @@ PWRITEV (int fd, const struct iovec *vector, int count, OFF_T offset)
      but 1. it is system specific (not meant in generic implementation), and
      2. it would make the implementation more complex, and 3. it will require
      another syscall (fcntl).  */
-  void *buffer = NULL;
-  if (__posix_memalign (&buffer, GLRO(dl_pagesize), bytes) != 0)
+  void *buffer = __mmap (NULL, bytes, PROT_WRITE,
+		         MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+  if (__glibc_unlikely (buffer == MAP_FAILED))
     return -1;
 
   /* Copy the data from BUFFER into the memory specified by VECTOR.  */
@@ -66,7 +68,7 @@ PWRITEV (int fd, const struct iovec *vector, int count, OFF_T offset)
 
   ssize_t ret = PWRITE (fd, buffer, bytes, offset);
 
-  free (buffer);
+  __munmap (buffer, bytes);
 
   return ret;
 }

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

Summary of changes:
 ChangeLog                      |    7 +++++++
 sysdeps/posix/preadv_common.c  |    8 +++++---
 sysdeps/posix/pwritev_common.c |    8 +++++---
 3 files changed, 17 insertions(+), 6 deletions(-)


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