Re: [PATCH] procfs: fix /proc/<pid>/maps heap check
From: Aaro Koskinen
Date: Wed Mar 02 2011 - 07:59:19 EST
Hi,
On Tue, 1 Mar 2011, Aaro Koskinen wrote:
The current check looks wrong and prints "[heap]" only if the mapping
matches exactly the heap. However, the heap may be merged with some
other mappings, and there may be also be multiple mappings.
Signed-off-by: Aaro Koskinen <aaro.koskinen@xxxxxxxxx>
Cc: stable@xxxxxxxxxx
Below is a test program and an example output showing the problem,
and the correct output with the patch:
Without the patch:
# ./a.out &
# cat /proc/$!/maps | head -4
00008000-00009000 r-xp 00000000 01:00 9224 /a.out
00010000-00011000 rw-p 00000000 01:00 9224 /a.out
00011000-00012000 rw-p 00000000 00:00 0
00012000-00013000 rw-p 00000000 00:00 0
With the patch:
# ./a.out &
# cat /proc/$!/maps | head -4
00008000-00009000 r-xp 00000000 01:00 9228 /a.out
00010000-00011000 rw-p 00000000 01:00 9228 /a.out
00011000-00012000 rw-p 00000000 00:00 0 [heap]
00012000-00013000 rw-p 00000000 00:00 0 [heap]
The test program:
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/mman.h>
int main (void)
{
if (sbrk(4096) == (void *)-1) {
perror("first sbrk(): ");
return EXIT_FAILURE;
}
if (mlockall(MCL_FUTURE)) {
perror("mlockall(): ");
return EXIT_FAILURE;
}
if (sbrk(4096) == (void *)-1) {
perror("second sbrk(): ");
return EXIT_FAILURE;
}
while (1)
sleep(1);
}
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