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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.
This commit is contained in:
Adhemerval Zanella 2017-11-22 18:02:20 -02:00
parent 3ffc4cc1ad
commit c45d78aac4
3 changed files with 17 additions and 6 deletions
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7
ChangeLog
View File

@ -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]

8
sysdeps/posix/preadv_common.c
View File

@ -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;
}

8
sysdeps/posix/pwritev_common.c
View File

@ -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;
}