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Thu, 2 Oct 2025 08:13:37 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id C2OkKzE03mhoUQAAD6G6ig (envelope-from ); Thu, 02 Oct 2025 08:13:37 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id 6C2DBA0A56; Thu, 2 Oct 2025 10:13:37 +0200 (CEST) From: Jan Kara To: Christian Brauner Cc: Dan Williams , , Matthew Wilcox , chao@kernel.org, linux-erofs@lists.ozlabs.org, Jan Kara , syzbot+47680984f2d4969027ea@syzkaller.appspotmail.com Subject: [PATCH] dax: fix assertion in dax_iomap_rw() Date: Thu, 2 Oct 2025 10:13:12 +0200 Message-ID: <20251002081311.10488-2-jack@suse.cz> X-Mailer: git-send-email 2.51.0 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=912; i=jack@suse.cz; h=from:subject; bh=UsMqyOIhr8WHIm6v1/phOHfCF4/wORmA8WhPGDaHvQU=; b=owEBbQGS/pANAwAIAZydqgc/ZEDZAcsmYgBo3jQXQ9++U/Immj1t7Q2t9La2rvw9BDT7qKvX4 aakZ8ucOJGJATMEAAEIAB0WIQSrWdEr1p4yirVVKBycnaoHP2RA2QUCaN40FwAKCRCcnaoHP2RA 2Z6yCADWOVDY5abLZ6s85kA8oXAY0ON0EFcqsNzUAOxR5+syzjr3MERold2c80b5sRUH/4g7CBV yWqyD8/D+Raml1imo1K7wJcQp94t2xlCRCutADrHW6vmo8Kk7sDNg79sBomyqZvo3FazOzpesvR 5TUe6esMFh2DCYomiSV9UuYL0rEl+q8HyxZ5yar89IpQd89e5btjoC4XZJQJ2vz4mnH3+hX/7R7 XNbs5czy365hJPGwBnr25CN87vcdz5A4ua5c8jhoXwpywav0rpSLGaMryatmtxFlBa8UxoKtzPf Z7YUk6NeBPEmr9VR7U4kMcImAMs7bj9/lPbQtQo7deOOxTLl X-Developer-Key: i=jack@suse.cz; 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DKIM_TRACE(0.00)[suse.cz:+]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns] X-Spam-Flag: NO X-Spam-Level: X-Rspamd-Queue-Id: BC67B1FB58 X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Action: no action X-Spam-Score: -1.51 dax_iomap_rw() asserts that inode lock is held when reading from it. The assert triggers on erofs as it indeed doesn't hold any locks in this case - naturally because there's nothing to race against when the filesystem is read-only. Check the locking only if the filesystem is actually writeable. Reported-by: syzbot+47680984f2d4969027ea@syzkaller.appspotmail.com Signed-off-by: Jan Kara --- fs/dax.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/dax.c b/fs/dax.c index 20ecf652c129..187f8c325744 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -1752,7 +1752,7 @@ dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter, if (iov_iter_rw(iter) == WRITE) { lockdep_assert_held_write(&iomi.inode->i_rwsem); iomi.flags |= IOMAP_WRITE; - } else { + } else if (!IS_RDONLY(iomi.inode)) { lockdep_assert_held(&iomi.inode->i_rwsem); } -- 2.51.0