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fsx: Add check for mmap last-page zero fill

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Check to make sure the VM system provided 0's beyond the true end of
the file mapping (as required by mmap def in 1996 posix 1003.1)

This check was taken from the FreeBSD version of fsx.c.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
This commit is contained in:
Theodore Ts'o
2009-05-13 15:52:42 -05:00
committed by Eric Sandeen
parent 969f36df3e
commit 6bb39a9df4
1 changed files with 35 additions and 0 deletions
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ltp/fsx.c
+35
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@@ -9,6 +9,8 @@
* Rewritten 8/98 by Conrad Minshall.
*
* Small changes to work under Linux -- davej.
*
* Checks for mmap last-page zero fill.
*/
#include "global.h"
@@ -503,6 +505,33 @@ doread(unsigned offset, unsigned size)
}
void
check_eofpage(char *s, unsigned offset, char *p, int size)
{
unsigned long last_page, should_be_zero;
if (offset + size <= (file_size & ~page_mask))
return;
/*
* we landed in the last page of the file
* test to make sure the VM system provided 0's
* beyond the true end of the file mapping
* (as required by mmap def in 1996 posix 1003.1)
*/
last_page = ((unsigned long)p + (offset & page_mask) + size) & ~page_mask;
for (should_be_zero = last_page + (file_size & page_mask);
should_be_zero < last_page + page_size;
should_be_zero++)
if (*(char *)should_be_zero) {
prt("Mapped %s: non-zero data past EOF (0x%llx) page offset 0x%x is 0x%04x\n",
s, file_size - 1, should_be_zero & page_mask,
short_at(should_be_zero));
report_failure(205);
}
}
void
domapread(unsigned offset, unsigned size)
{
@@ -547,6 +576,9 @@ domapread(unsigned offset, unsigned size)
report_failure(190);
}
memcpy(temp_buf, p + pg_offset, size);
check_eofpage("Read", offset, p, size);
if (munmap(p, map_size) != 0) {
prterr("domapread: munmap");
report_failure(191);
@@ -696,6 +728,9 @@ domapwrite(unsigned offset, unsigned size)
prterr("domapwrite: msync");
report_failure(203);
}
check_eofpage("Write", offset, p, size);
if (munmap(p, map_size) != 0) {
prterr("domapwrite: munmap");
report_failure(204);