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[131.94.134.89]) by smtp.gmail.com with ESMTPSA id 71dfb90a1353d-5c3d05c594fsm3706321e0c.8.2026.08.06.09.59.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Aug 2026 09:59:10 -0700 (PDT) From: Chao Shi To: Jan Kara , Christian Brauner , Alexander Viro , Matthew Wilcox , linux-fsdevel@vger.kernel.org Cc: Theodore Ts'o , Andreas Dilger , Baokun Li , Ojaswin Mujoo , Ritesh Harjani , Zhang Yi , Zhang Yi , Bob Copeland , Namjae Jeon , Sungjong Seo , Yuezhang Mo , OGAWA Hirofumi , Mark Fasheh , Joel Becker , Joseph Qi , Andreas Gruenbacher , linux-ext4@vger.kernel.org, ocfs2-devel@lists.linux.dev, gfs2@lists.linux.dev, linux-kernel@vger.kernel.org, Chao Shi , Weidong Zhu Subject: [PATCH v2 04/21] buffer: read the folio's mapping directly in buffer_set_crypto_ctx() Date: Thu, 6 Aug 2026 12:58:27 -0400 Message-ID: <3fe72ec37bf8491a69031db5f3ba1319da935b97.1785951556.git.coshi036@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit folio_mapping() was doing two jobs here. One was to turn a slab folio into NULL, which is what made this safe for jbd2's shadow buffers; the previous patch removed the need for that by giving those buffers no folio at all. The other is a hazard. folio_mapping() maps a folio in the swap cache to its swap_address_space, so if a buffer_head were ever attached to such a folio this would hand fscrypt a swap mapping and dereference ->host on it. There is no reason to want that here: this path wants the file's mapping or nothing. Read ->mapping directly. Buffers with no folio are already handled above. Suggested-by: Matthew Wilcox (Oracle) Acked-by: Weidong Zhu Signed-off-by: Chao Shi --- fs/buffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/buffer.c b/fs/buffer.c index 04fcc34e4fa6..2851830995d8 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -1108,7 +1108,7 @@ static void buffer_set_crypto_ctx(struct bio *bio, const struct buffer_head *bh, */ if (!bh->b_folio) return; - mapping = folio_mapping(bh->b_folio); + mapping = bh->b_folio->mapping; if (!mapping) return; fscrypt_set_bio_crypt_ctx(bio, mapping->host, -- 2.43.0