kernel/linux.git/fs/sysfs/file.c, branch v6.12.97

sysfs: clamp show() return value in sysfs_kf_read()

2026-07-24T14:10:47+00:00

[ Upstream commit 454257f6d124a92342dcbb7710c03dd6ef96c731 ] sysfs_kf_seq_show() defends against buggy show() callbacks that return larger than PAGE_SIZE by clamping the value and printing a warning. sysfs_kf_read(), the prealloc variant, has no such defense. The only current in-tree user of __ATTR_PREALLOC is drivers/md/md.c, whose show() callbacks are well-behaved, so this is hardening against future drivers doing foolish things and out-of-tree code doing even more foolish things. Cc: NeilBrown Cc: Tejun Heo Fixes: 2b75869bba67 ("sysfs/kernfs: allow attributes to request write buffer be pre-allocated.") Assisted-by: gregkh_clanker_t1000 Reviewed-by: Rafael J. Wysocki (Intel) Reviewed-by: Danilo Krummrich Link: https://patch.msgid.link/2026052000-drove-unicycle-d61b@gregkh Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

Merge 6.9-rc5 into driver-core-next

2024-04-23T11:27:43+00:00

We want the kernfs fixes in here as well. Signed-off-by: Greg Kroah-Hartman

sysfs: Add sysfs_bin_attr_simple_read() helper

2024-04-11T14:02:25+00:00

When drivers expose a bin_attribute in sysfs which is backed by a buffer in memory, a common pattern is to set the @private and @size members in struct bin_attribute to the buffer's location and size. The ->read() callback then merely consists of a single memcpy() call. It's not even necessary to perform bounds checks as these are already handled by sysfs_kf_bin_read(). However each driver is so far providing its own ->read() implementation. The pattern is sufficiently frequent to merit a public helper, so add sysfs_bin_attr_simple_read() as well as BIN_ATTR_SIMPLE_RO() and BIN_ATTR_SIMPLE_ADMIN_RO() macros to ease declaration of such bin_attributes and reduce LoC and .text section size. Signed-off-by: Lukas Wunner Reviewed-by: Greg Kroah-Hartman Acked-by: Rafael J. Wysocki Acked-by: Ard Biesheuvel Link: https://lore.kernel.org/r/5ed62b197a442ec6db53d8746d9d806dd0576e2d.1712410202.git.lukas@wunner.de Signed-off-by: Greg Kroah-Hartman

fs: sysfs: Fix reference leak in sysfs_break_active_protection()

2024-04-11T13:16:48+00:00

The sysfs_break_active_protection() routine has an obvious reference leak in its error path. If the call to kernfs_find_and_get() fails then kn will be NULL, so the companion sysfs_unbreak_active_protection() routine won't get called (and would only cause an access violation by trying to dereference kn->parent if it was called). As a result, the reference to kobj acquired at the start of the function will never be released. Fix the leak by adding an explicit kobject_put() call when kn is NULL. Signed-off-by: Alan Stern Fixes: 2afc9166f79b ("scsi: sysfs: Introduce sysfs_{un,}break_active_protection()") Cc: Bart Van Assche Cc: stable@vger.kernel.org Reviewed-by: Bart Van Assche Acked-by: Tejun Heo Link: https://lore.kernel.org/r/8a4d3f0f-c5e3-4b70-a188-0ca433f9e6f9@rowland.harvard.edu Signed-off-by: Greg Kroah-Hartman

kernfs: sysfs: support custom llseek method for sysfs entries

2023-10-05T11:42:11+00:00

As of now, seeking in sysfs files is handled by generic_file_llseek(). There are situations where one may want to customize seeking logic: - Many sysfs entries are fixed files while generic_file_llseek() accepts past-the-end positions. Not only being useless by itself, this also means a bug in userspace code will trigger not at lseek(), but at some later point making debugging harder. - generic_file_llseek() relies on f_mapping->host to get the file size which might not be correct for all sysfs entries. See commit 636b21b50152 ("PCI: Revoke mappings like devmem") as an example. Implement llseek method to override this behavior at sysfs attribute level. The method is optional, and if it is absent, generic_file_llseek() is called to preserve backwards compatibility. Signed-off-by: Valentine Sinitsyn Link: https://lore.kernel.org/r/20230925084013.309399-1-valesini@yandex-team.ru Signed-off-by: Greg Kroah-Hartman

kobject: kobj_type: remove default_attrs

2022-04-05T13:39:19+00:00

Now that all in-kernel users of default_attrs for the kobj_type are gone and converted to properly use the default_groups pointer instead, it can be safely removed. There is one standard way to create sysfs files in a kobj_type, and not two like before, causing confusion as to which should be used. Cc: "Rafael J. Wysocki" Link: https://lore.kernel.org/r/20220106133151.607703-1-gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman

sysfs: simplify sysfs_kf_seq_show

2021-09-14T15:03:01+00:00

Contrary to the comment ->show is never called from lseek for sysfs, given that sysfs does not use seq_lseek. So remove the NULL ->show case and just WARN and return an error if some future code path ends up here. Acked-by: Tejun Heo Signed-off-by: Christoph Hellwig Link: https://lore.kernel.org/r/20210913054121.616001-7-hch@lst.de Signed-off-by: Greg Kroah-Hartman

sysfs: refactor sysfs_add_file_mode_ns

2021-09-14T15:02:58+00:00

Regroup the code so that preallocated attributes and normal attributes are handled in clearly separate blocks. Acked-by: Christian Brauner Acked-by: Tejun Heo Signed-off-by: Christoph Hellwig Link: https://lore.kernel.org/r/20210913054121.616001-6-hch@lst.de Signed-off-by: Greg Kroah-Hartman

sysfs: split out binary attribute handling from sysfs_add_file_mode_ns

2021-09-14T14:59:46+00:00

Split adding binary attributes into a separate handler instead of overloading sysfs_add_file_mode_ns. Acked-by: Christian Brauner Acked-by: Tejun Heo Signed-off-by: Christoph Hellwig Link: https://lore.kernel.org/r/20210913054121.616001-5-hch@lst.de Signed-off-by: Greg Kroah-Hartman

sysfs: Rename struct bin_attribute member to f_mapping

2021-08-05T12:47:31+00:00

There are two users of iomem_get_mapping(), the struct file and struct bin_attribute. The former has a member called "f_mapping" and the latter has a member called "mapping", and both are poniters to struct address_space. Rename struct bin_attribute member to "f_mapping" to keep both meaning and the usage consistent with other users of iomem_get_mapping(). Acked-by: Bjorn Helgaas Signed-off-by: Krzysztof Wilczyński Link: https://lore.kernel.org/r/20210729233235.1508920-3-kw@linux.com Signed-off-by: Greg Kroah-Hartman