This change does introduce an API change, and a somewhat possibly dangerous
structure size alteration, and seems to be out of bounds for apr 1.7.x
branch, as
identified in the commit message.
Anyone using a build crossing runtimes between apr 1.7.0 and 1.7.1 may
experience
unintended side-effects. The eventual change still is present for apr
1.8 adopters.
Thoughts? ylavic are you willing to revert?
On Thu, Mar 11, 2021 at 10:21 AM wrote:
>
> Author: ylavic
> Date: Thu Mar 11 16:21:07 2021
> New Revision: 1887497
>
> URL: http://svn.apache.org/viewvc?rev=1887497=rev
> Log:
> Merge r1887060 from trunk:
>
> Align apr_mmap()ing offset to a page boundary. PR 65158.
>
> This is requirement for unix systems, and otherwise can cause failures or
> undefined behaviour with some filesystems.
>
> Add apr_mmap_t->poffset on unixes to track the offset to the previous page,
> relative to the user requested/actual offset. This allows ->mm and ->size to
> still point to the actual data, while munmap() now deletes the full range
> from the start of the page.
>
> Tests updated accordingly.
>
>
> * Changes between r1887060 and this 1.7.x backport
>
> Since the layout of struct apr_mmap_t cannot change (non opaque), the poffset
> is over-allocated in mmap/unix/mmap.cmmap.c which uses this layout internally:
> struct mm_layout {
> apr_mmap_t mm;
> apr_off_t poffset;
> };
>
> This works for all the apr_mmap_t created by apr_mmap_create() with which any
> apr_mmap_*() function can then be called.
>
> If a user creates an apr_mmap_t "by hand", with this change it cannot be
> passed
> to apr_mmap_dup() without causing an out-of-bound read. This is hardly a new
> limitation though, the refcounting which is the point of apr_mmap_dup() and
> apr_mmap_delete() comes from the private function mmap_cleanup() anyway, so
> there is no point in using these two functions with hand made apr_mmap_t (if
> there ever was a point in the first place to create an hand made
> apr_mmap_t..).
>
>
> Submitted by: ylavic
>
> Added:
> apr/apr/branches/1.7.x/test/data/mmap_large_datafile.txt
> - copied unchanged from r1887060,
> apr/apr/trunk/test/data/mmap_large_datafile.txt
> Modified:
> apr/apr/branches/1.7.x/ (props changed)
> apr/apr/branches/1.7.x/CHANGES
> apr/apr/branches/1.7.x/mmap/unix/mmap.c
> apr/apr/branches/1.7.x/test/testfnmatch.c
> apr/apr/branches/1.7.x/test/testmmap.c
>
> Propchange: apr/apr/branches/1.7.x/
> --
> Merged /apr/apr/trunk:r1887060
>
> Modified: apr/apr/branches/1.7.x/CHANGES
> URL:
> http://svn.apache.org/viewvc/apr/apr/branches/1.7.x/CHANGES?rev=1887497=1887496=1887497=diff
> ==
> --- apr/apr/branches/1.7.x/CHANGES [utf-8] (original)
> +++ apr/apr/branches/1.7.x/CHANGES [utf-8] Thu Mar 11 16:21:07 2021
> @@ -1,6 +1,8 @@
> -*- coding: utf-8 -*-
> Changes for APR 1.7.1
>
> + *) Align apr_mmap()ing offset to a page boundary. PR 65158. [Yann Ylavic]
> +
>*) Don't silently set APR_FOPEN_NOCLEANUP for apr_file_mktemp() created
> file
> to avoid a fd and inode leak when/if later passed to
> apr_file_setaside().
> [Yann Ylavic]
>
> Modified: apr/apr/branches/1.7.x/mmap/unix/mmap.c
> URL:
> http://svn.apache.org/viewvc/apr/apr/branches/1.7.x/mmap/unix/mmap.c?rev=1887497=1887496=1887497=diff
> ==
> --- apr/apr/branches/1.7.x/mmap/unix/mmap.c (original)
> +++ apr/apr/branches/1.7.x/mmap/unix/mmap.c Thu Mar 11 16:21:07 2021
> @@ -14,6 +14,8 @@
> * limitations under the License.
> */
>
> +#include
> +
> #include "apr.h"
> #include "apr_private.h"
> #include "apr_general.h"
> @@ -33,6 +35,9 @@
> #if APR_HAVE_STDIO_H
> #include
> #endif
> +#if APR_HAVE_UNISTD_H
> +#include /* for sysconf() */
> +#endif
> #ifdef HAVE_SYS_STAT_H
> #include
> #endif
> @@ -42,6 +47,34 @@
>
> #if APR_HAS_MMAP || defined(BEOS)
>
> +#ifndef BEOS
> +struct mm_layout {
> +apr_mmap_t mm;
> +apr_off_t poffset;
> +};
> +
> +static APR_INLINE
> +apr_mmap_t *alloc_with_poffset(apr_pool_t *p)
> +{
> +struct mm_layout *layout = apr_pcalloc(p, sizeof(*layout));
> +return >mm;
> +}
> +
> +static APR_INLINE
> +void set_poffset(apr_mmap_t *mm, apr_off_t poffset)
> +{
> +struct mm_layout *layout = (struct mm_layout *)mm;
> +layout->poffset = poffset;
> +}
> +
> +static APR_INLINE
> +apr_off_t get_poffset(apr_mmap_t *mm)
> +{
> +struct mm_layout *layout = (struct mm_layout *)mm;
> +return layout->poffset;
> +}
> +#endif
> +
> static apr_status_t mmap_cleanup(void *themmap)
> {
> apr_mmap_t *mm = themmap;
> @@ -61,7 +94,7 @@ static apr_status_t mmap_cleanup(void *t
> #ifdef BEOS
> rv = delete_area(mm->area);
> #else
> -rv = munmap(mm->mm,
