From: Pavel Begunkov Date: Tue, 24 Jun 2025 13:40:34 +0000 (+0100) Subject: io_uring/rsrc: don't rely on user vaddr alignment X-Git-Tag: v6.16-rc4~19^2~4 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=3a3c6d61577dbb23c09df3e21f6f9eda1ecd634b;p=thirdparty%2Fkernel%2Fstable.git io_uring/rsrc: don't rely on user vaddr alignment There is no guaranteed alignment for user pointers, however the calculation of an offset of the first page into a folio after coalescing uses some weird bit mask logic, get rid of it. Cc: stable@vger.kernel.org Reported-by: David Hildenbrand Fixes: a8edbb424b139 ("io_uring/rsrc: enable multi-hugepage buffer coalescing") Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/io-uring/e387b4c78b33f231105a601d84eefd8301f57954.1750771718.git.asml.silence@gmail.com/ Signed-off-by: Jens Axboe --- diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c index 0c09e38784c9..afc67530f912 100644 --- a/io_uring/rsrc.c +++ b/io_uring/rsrc.c @@ -734,6 +734,7 @@ bool io_check_coalesce_buffer(struct page **page_array, int nr_pages, data->nr_pages_mid = folio_nr_pages(folio); data->folio_shift = folio_shift(folio); + data->first_folio_page_idx = folio_page_idx(folio, page_array[0]); /* * Check if pages are contiguous inside a folio, and all folios have @@ -827,7 +828,11 @@ static struct io_rsrc_node *io_sqe_buffer_register(struct io_ring_ctx *ctx, if (coalesced) imu->folio_shift = data.folio_shift; refcount_set(&imu->refs, 1); - off = (unsigned long) iov->iov_base & ((1UL << imu->folio_shift) - 1); + + off = (unsigned long)iov->iov_base & ~PAGE_MASK; + if (coalesced) + off += data.first_folio_page_idx << PAGE_SHIFT; + node->buf = imu; ret = 0; diff --git a/io_uring/rsrc.h b/io_uring/rsrc.h index 0d2138f16322..25e7e998dcfd 100644 --- a/io_uring/rsrc.h +++ b/io_uring/rsrc.h @@ -49,6 +49,7 @@ struct io_imu_folio_data { unsigned int nr_pages_mid; unsigned int folio_shift; unsigned int nr_folios; + unsigned long first_folio_page_idx; }; bool io_rsrc_cache_init(struct io_ring_ctx *ctx);