Bruce Dubbs wrote:
When testing an installation with tests from the Linux Test Project, my
kernels fail one instance of the mincore01 tests:
mincoremincore01 1 PASS : expected failure: errno = 22 (Invalid
argument)
mincore01 2 PASS : expected failure: errno = 14 (Bad address)
mincore01 3 FAIL : call succeeded unexpectedly
mincore01 4 PASS : expected failure: errno = 12 (Cannot allocate
memory)01 1 PASS : expected failure: errno = 22 (Invalid argument)
mincore01 2 PASS : expected failure: errno = 14 (Bad address)
mincore01 3 FAIL : call succeeded unexpectedly
mincore01 4 PASS : expected failure: errno = 12 (Cannot allocate
memory)
I pared down the test to the attached program. The result is supposed
to fail as it is asking for memory information 5 times what should be
allocated.
Upon experimenting, I found the test works properly if a printf is
executed before the mmap call. I have tested on locally built, but
unmodified, 2.4.25, 2.6.12.5, and a 2.6.20.3 kernels and get the same
behavior. The tests fail on IA32 architecture, but not 64-bit kernels.
The test always works properly on FC6 and RHEL3.
I've checked the archives for this issue and could not find anything
appropriate.
Could this be a potential security issue as memory that is not supposed
to be accessible seems to be available to the user? Is it expected
behavior?
It shouldn't be a security problem if mincore doesn't actually
return the data.
The other thing is, that test may not be valid, because it doesn't
guarantee that you have nothing mapped immediately after the
global_pointer region. Maybe a difference in address space layout
is causing it to "correctly" fail on x86-64.
Thanks.
-- Bruce
------------------------------------------------------------------------
#include <sys/mman.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
static int PAGESIZE;
static char file_name[] = "fooXXXXXX";
static void* global_pointer = NULL;
static int global_len = 0;
static int file_desc = 0;
int main(int argc, char **argv)
{
int i;
int result;
char* buf;
unsigned char vect[20] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
PAGESIZE = getpagesize();
/* global_pointer will point to a mmapped area of global_len bytes */
global_len = PAGESIZE*2;
buf = (char*)malloc(global_len);
memset(buf, 42, global_len); // Asterisks
/* create a temporary file */
file_desc = mkstemp(file_name);
/* fill the temporary file with two pages of data */
write(file_desc, buf, global_len);
free(buf);
// Will work properly as long as print is before mmap function.
if ( argc > 1 ) printf("argc=%d\n", argc);
/* map the file in memory */
global_pointer = mmap( NULL, global_len,
PROT_READ|PROT_WRITE|PROT_EXEC, MAP_SHARED, file_desc, 0);
// Result should be -1 as the request is 5 times actual mapping
result = mincore(global_pointer, (size_t)(global_len*5), vect);
// Print some data
printf("PAGESIZE=%d\n", PAGESIZE);
printf("global_len=%d\n", global_len);
printf("global_pointer=0x%x\n", (unsigned int)global_pointer);
printf("alloc=%d\n", (global_len+PAGESIZE-1) / PAGESIZE );
printf("Result=%d\n", result);
printf("vect: ");
for ( i=0; i<20; i++) printf("%02x ", vect[i]);
printf("\n");
// Clean up
munmap(global_pointer, (size_t)global_len);
close(file_desc);
unlink(file_name);
}
--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/