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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kees Cook , Peter Zijlstra , Jann Horn , Pedro Falcato , Hugh Dickins , Pasha Tatashin , Pratyush Yadav , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Lance Yang , Rik van Riel , Harry Yoo , Alistair Popple , Nico Pache , Ryan Roberts , Dev Jain , Usama Arif , Kiryl Shutsemau , Matthew Brost , John Hubbard , Peter Xu , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Oscar Salvador , Minchan Kim , Muchun Song , Xu Xin , Chengming Zhou , Chris Li , Kemeng Shi , Nhat Pham , Youngjun Park , Gregory Price , Joshua Hahn , Rakie Kim , Ying Huang , Jason Gunthorpe Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, stable@vger.kernel.org, Chris Mason , "David Hildenbrand (Arm)" X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3445; i=david@kernel.org; h=from:subject:message-id; bh=72FnFCPclMGQ2RVEjfTEZip7yxNcpfMMwjBpW8uk9h8=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLLu3598IHG65lsVvXN7Xh/+NOGzlVBY7sGdTtrcVexbt 0vN3xRZ3VHKwiDGwSArpsgSFHzf4OXLdbXVbnzMMHNYmUCGMHBxCsBEbnIxMqw+svrQr1oPlhsX rM+erHVStVc64N6aKaOqvXX5p761hzUY/hdIXvknGLTOdA1flFehtk0aT5N8nNyinpZ3zf/vbl9 0lREA X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: D419FC0005 X-Spam-Status: No, score=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=4.0.1 X-Stat-Signature: hrode719un5qe64z8sj68beek64bidjg X-HE-Tag: 1793056730-241665 X-HE-Meta: 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 gB74Uoqm 1jKWWI9cs+1nQWNOX6MDAKIk/9XBMATIPLSNDMVUGpJ84Axljq4GY0lZ/0KR7hNPecWcCkKelxyGKOYB9T+ldStAAVjXWQYpo6WPDUaVQEfiK6IeZ8NsPMV0oHn4laAvjZri4Lxei3NF0fL2NjgZKQeJnTv5bTV7uxAxiMaiQ5BffyZNVeWWFoXOzE25F4xq/oupnTqAWAFOK2oNS/f4scSNgh3+gDBW88bsiluaS3MfC4wBIjhRqtZnlcSFqb0lRj27P49fNUeGWSa+3h5Ih9wP/66HQM84Hvh+FcwC1C/d83Wxdw2txn3t0aqTIccArWhAb Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 shmem_file() only checks a file's backing mapping. That mapping can belong to another file, as with a Coda file backed by a tmpfs container after mmap(). It does not establish that file_inode(file) is a shmem inode. Seal handling and memfd preservation use this check before accessing shmem inode state, so they can access an inode of the wrong type. Add file_inode_is_shmem() to check the inode's file operations in both paths. This identifies regular shmem inodes, including those used by memfds and ordinary tmpfs files, independently of wrapper file operations. Fixes: c49fcfcda8b5 ("mm/shmem: update file sealing comments and file checking") Fixes: b3749f174d68 ("mm: memfd_luo: allow preserving memfd") Cc: stable@vger.kernel.org Reported-by: Chris Mason Signed-off-by: David Hildenbrand (Arm) --- include/linux/shmem_fs.h | 6 ++++++ mm/memfd.c | 8 +++++--- mm/memfd_luo.c | 2 +- mm/shmem.c | 5 +++++ 4 files changed, 17 insertions(+), 4 deletions(-) diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h index a7c7a96a7cbf9..2ceca7993e4f5 100644 --- a/include/linux/shmem_fs.h +++ b/include/linux/shmem_fs.h @@ -117,8 +117,14 @@ extern unsigned long shmem_get_unmapped_area(struct file *, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags); extern int shmem_lock(struct file *file, int lock, struct ucounts *ucounts); #ifdef CONFIG_SHMEM +bool file_inode_is_shmem(const struct inode *inode); bool shmem_mapping(const struct address_space *mapping); #else +static inline bool file_inode_is_shmem(const struct inode *inode) +{ + return false; +} + static inline bool shmem_mapping(const struct address_space *mapping) { return false; diff --git a/mm/memfd.c b/mm/memfd.c index 0f6fff004f5e4..7d2da23157003 100644 --- a/mm/memfd.c +++ b/mm/memfd.c @@ -211,12 +211,14 @@ static int memfd_wait_for_pins(struct address_space *mapping) static unsigned int *memfd_file_seals_ptr(struct file *file) { - if (shmem_file(file)) - return &SHMEM_I(file_inode(file))->seals; + struct inode *inode = file_inode(file); + + if (file_inode_is_shmem(inode)) + return &SHMEM_I(inode)->seals; #ifdef CONFIG_HUGETLBFS if (is_file_hugepages(file)) - return &HUGETLBFS_I(file_inode(file))->seals; + return &HUGETLBFS_I(inode)->seals; #endif return NULL; diff --git a/mm/memfd_luo.c b/mm/memfd_luo.c index 59de210bee5f9..c0811407ce397 100644 --- a/mm/memfd_luo.c +++ b/mm/memfd_luo.c @@ -582,7 +582,7 @@ static bool memfd_luo_can_preserve(struct liveupdate_file_handler *handler, { struct inode *inode = file_inode(file); - return shmem_file(file) && !inode->i_nlink; + return file_inode_is_shmem(inode) && !inode->i_nlink; } static unsigned long memfd_luo_get_id(struct file *file) diff --git a/mm/shmem.c b/mm/shmem.c index fadf23f9e21ed..0d41aac125df9 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -275,6 +275,11 @@ static const struct vm_operations_struct shmem_vm_ops; static const struct vm_operations_struct shmem_anon_vm_ops; static struct file_system_type shmem_fs_type; +bool file_inode_is_shmem(const struct inode *inode) +{ + return inode->i_fop == &shmem_file_operations; +} + bool shmem_mapping(const struct address_space *mapping) { return mapping->a_ops == &shmem_aops; -- 2.43.0