On Tue, Sep 4, 2012 at 5:23 AM, Wanlong Gao <gaowanlong@xxxxxxxxxxxxxx> wrote:
> POSIX said that if the file is a regular file and the value of "off"
> plus "len" exceeds the offset maximum established in the open file
> description associated with fildes, mmap should return EOVERFLOW.
>
> The following test from LTP can reproduce this bug.
>
> char tmpfname[256];
> void *pa = NULL;
> void *addr = NULL;
> size_t len;
> int flag;
> int fd;
> off_t off = 0;
> int prot;
>
> long page_size = sysconf(_SC_PAGE_SIZE);
>
> snprintf(tmpfname, sizeof(tmpfname), "/tmp/mmap_test_%d", getpid());
> unlink(tmpfname);
> fd = open(tmpfname, O_CREAT | O_RDWR | O_EXCL, S_IRUSR | S_IWUSR);
> if (fd == -1) {
> printf(" Error at open(): %s\n", strerror(errno));
> return 1;
> }
> unlink(tmpfname);
>
> flag = MAP_SHARED;
> prot = PROT_READ | PROT_WRITE;
>
> /* len + off > maximum offset */
>
> len = ULONG_MAX;
> if (len % page_size) {
> /* Lower boundary */
> len &= ~(page_size - 1);
> }
>
> off = ULONG_MAX;
> if (off % page_size) {
> /* Lower boundary */
> off &= ~(page_size - 1);
> }
>
> printf("off: %lx, len: %lx\n", (unsigned long)off, (unsigned long)len);
> pa = mmap(addr, len, prot, flag, fd, off);
> if (pa == MAP_FAILED && errno == EOVERFLOW) {
> printf("Test Pass: Error at mmap: %s\n", strerror(errno));
> return 0;
> }
>
> if (pa == MAP_FAILED)
> perror("Test FAIL: expect EOVERFLOW but get other error");
> else
> printf("Test FAIL : Expect EOVERFLOW but got no error\n");
>
> close(fd);
> munmap(pa, len);
> return 1;
>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
> Cc: linux-mm@xxxxxxxxx (open list:MEMORY MANAGEMENT)
> Signed-off-by: Wanlong Gao <gaowanlong@xxxxxxxxxxxxxx>
> ---
> mm/mmap.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/mm/mmap.c b/mm/mmap.c
> index ae18a48..5380764 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -980,6 +980,7 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
> struct mm_struct * mm = current->mm;
> struct inode *inode;
> vm_flags_t vm_flags;
> + off_t off = pgoff << PAGE_SHIFT;
I've seen the exactly same patch from another fujitsu guys several
month ago. and as I pointed
out at that time, this line don't work when 32bit kernel + mmap2 syscall case.
Please don't think do_mmap_pgoff() is for mmap(2) specific and read a
past thread before resend
a patch.
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