| Message ID | 20221018090323.never.897-kees@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mempool: Use kmalloc_size_roundup() to match ksize() usage | expand |
On Tue, 18 Oct 2022 02:03:29 -0700 Kees Cook <keescook@chromium.org> wrote: > Round up allocations with kmalloc_size_roundup() so that mempool's use > of ksize() is always accurate and no special handling of the memory is > needed by KASAN, UBSAN_BOUNDS, nor FORTIFY_SOURCE. Confused. If the special handling is not needed, why doesn't the patch removed the no longer needed special handling? > > diff --git a/mm/mempool.c b/mm/mempool.c > index 96488b13a1ef..0f3107b28e6b 100644 > --- a/mm/mempool.c > +++ b/mm/mempool.c > @@ -526,7 +526,7 @@ EXPORT_SYMBOL(mempool_free_slab); > */ > void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data) > { > - size_t size = (size_t)pool_data; > + size_t size = kmalloc_size_roundup((size_t)pool_data); > return kmalloc(size, gfp_mask); > } > EXPORT_SYMBOL(mempool_kmalloc); > -- > 2.34.1
On Tue, Oct 18, 2022 at 03:51:37PM -0700, Andrew Morton wrote: > On Tue, 18 Oct 2022 02:03:29 -0700 Kees Cook <keescook@chromium.org> wrote: > > > Round up allocations with kmalloc_size_roundup() so that mempool's use > > of ksize() is always accurate and no special handling of the memory is > > needed by KASAN, UBSAN_BOUNDS, nor FORTIFY_SOURCE. > > Confused. If the special handling is not needed, why doesn't the patch > removed the no longer needed special handling? The special handling is in the ksize() implementation, so it can't be removed[1] until all the ksize()-affected users are updated to see their true allocation sizes first. [1] https://lore.kernel.org/lkml/20220923202822.2667581-16-keescook@chromium.org/
On 10/19/22 07:37, Kees Cook wrote: > On Tue, Oct 18, 2022 at 03:51:37PM -0700, Andrew Morton wrote: >> On Tue, 18 Oct 2022 02:03:29 -0700 Kees Cook <keescook@chromium.org> wrote: >> >> > Round up allocations with kmalloc_size_roundup() so that mempool's use >> > of ksize() is always accurate and no special handling of the memory is >> > needed by KASAN, UBSAN_BOUNDS, nor FORTIFY_SOURCE. >> >> Confused. If the special handling is not needed, why doesn't the patch >> removed the no longer needed special handling? > > The special handling is in the ksize() implementation, so it can't be > removed[1] until all the ksize()-affected users are updated to see their > true allocation sizes first. > > [1] https://lore.kernel.org/lkml/20220923202822.2667581-16-keescook@chromium.org/ But in the previous version I was wondering if we can just stop doing ksize()-like poison handling in mempool completely, if no mempool consumers call ksize() to expand their use of the allocated objects. You seemed to agree but this version is uncahnged? https://lore.kernel.org/all/f4fc52c4-7c18-1d76-0c7a-4058ea2486b9@suse.cz/
On Mon, Oct 24, 2022 at 08:03:34PM +0200, Vlastimil Babka (SUSE) wrote: > On 10/19/22 07:37, Kees Cook wrote: > > On Tue, Oct 18, 2022 at 03:51:37PM -0700, Andrew Morton wrote: > >> On Tue, 18 Oct 2022 02:03:29 -0700 Kees Cook <keescook@chromium.org> wrote: > >> > >> > Round up allocations with kmalloc_size_roundup() so that mempool's use > >> > of ksize() is always accurate and no special handling of the memory is > >> > needed by KASAN, UBSAN_BOUNDS, nor FORTIFY_SOURCE. > >> > >> Confused. If the special handling is not needed, why doesn't the patch > >> removed the no longer needed special handling? > > > > The special handling is in the ksize() implementation, so it can't be > > removed[1] until all the ksize()-affected users are updated to see their > > true allocation sizes first. > > > > [1] https://lore.kernel.org/lkml/20220923202822.2667581-16-keescook@chromium.org/ > > But in the previous version I was wondering if we can just stop doing > ksize()-like poison handling in mempool completely, if no mempool consumers > call ksize() to expand their use of the allocated objects. You seemed to > agree but this version is uncahnged? > > https://lore.kernel.org/all/f4fc52c4-7c18-1d76-0c7a-4058ea2486b9@suse.cz/ Oops, yes. This failed to get on my TODO list. New version coming!
diff --git a/mm/mempool.c b/mm/mempool.c index 96488b13a1ef..0f3107b28e6b 100644 --- a/mm/mempool.c +++ b/mm/mempool.c @@ -526,7 +526,7 @@ EXPORT_SYMBOL(mempool_free_slab); */ void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data) { - size_t size = (size_t)pool_data; + size_t size = kmalloc_size_roundup((size_t)pool_data); return kmalloc(size, gfp_mask); } EXPORT_SYMBOL(mempool_kmalloc);
Round up allocations with kmalloc_size_roundup() so that mempool's use of ksize() is always accurate and no special handling of the memory is needed by KASAN, UBSAN_BOUNDS, nor FORTIFY_SOURCE. Cc: Andrew Morton <akpm@linux-foundation.org> Cc: linux-mm@kvack.org Signed-off-by: Kees Cook <keescook@chromium.org> --- mm/mempool.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)