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| author | André Almeida <andrealmeid@igalia.com> | 2024-11-01 13:42:50 -0300 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2024-11-06 11:22:20 +0100 |
| commit | 18d2f10f6284f5bb9c03a759044121c71e5b3b4c (patch) | |
| tree | aefc2de0be279347a9f1d6c4054ff398cd06dd21 /mm/shmem.c | |
| parent | 33b091c08ed85e023c21376e6f787355fd46b440 (diff) | |
| download | lwn-18d2f10f6284f5bb9c03a759044121c71e5b3b4c.tar.gz lwn-18d2f10f6284f5bb9c03a759044121c71e5b3b4c.zip | |
tmpfs: Fix type for sysfs' casefold attribute
DEVICE_STRING_ATTR_RO should be only used by device drivers since it
relies on `struct device` to use device_show_string() function. Using
this with non device code led to a kCFI violation:
> cat /sys/fs/tmpfs/features/casefold
[ 70.558496] CFI failure at kobj_attr_show+0x2c/0x4c (target: device_show_string+0x0/0x38; expected type: 0xc527b809)
Like the other filesystems, fix this by manually declaring the attribute
using kobj_attribute() and writing a proper show() function.
Also, leave macros for anyone that need to expand tmpfs sysfs' with
more attributes.
Fixes: 5132f08bd332 ("tmpfs: Expose filesystem features via sysfs")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Closes: https://lore.kernel.org/lkml/20241031051822.GA2947788@thelio-3990X/
Signed-off-by: André Almeida <andrealmeid@igalia.com>
Link: https://lore.kernel.org/r/20241101164251.327884-3-andrealmeid@igalia.com
Tested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat (limited to 'mm/shmem.c')
| -rw-r--r-- | mm/shmem.c | 29 |
1 files changed, 27 insertions, 2 deletions
diff --git a/mm/shmem.c b/mm/shmem.c index 0739143d1419..00ff7ef16dc6 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -5548,13 +5548,38 @@ struct page *shmem_read_mapping_page_gfp(struct address_space *mapping, EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp); #if defined(CONFIG_SYSFS) && defined(CONFIG_TMPFS) + +#define __INIT_KOBJ_ATTR(_name, _mode, _show, _store) \ +{ \ + .attr = { .name = __stringify(_name), .mode = _mode }, \ + .show = _show, \ + .store = _store, \ +} + +#define TMPFS_ATTR_W(_name, _store) \ + static struct kobj_attribute tmpfs_attr_##_name = \ + __INIT_KOBJ_ATTR(_name, 0200, NULL, _store) + +#define TMPFS_ATTR_RW(_name, _show, _store) \ + static struct kobj_attribute tmpfs_attr_##_name = \ + __INIT_KOBJ_ATTR(_name, 0644, _show, _store) + +#define TMPFS_ATTR_RO(_name, _show) \ + static struct kobj_attribute tmpfs_attr_##_name = \ + __INIT_KOBJ_ATTR(_name, 0444, _show, NULL) + #if IS_ENABLED(CONFIG_UNICODE) -static DEVICE_STRING_ATTR_RO(casefold, 0444, "supported"); +static ssize_t casefold_show(struct kobject *kobj, struct kobj_attribute *a, + char *buf) +{ + return sysfs_emit(buf, "supported\n"); +} +TMPFS_ATTR_RO(casefold, casefold_show); #endif static struct attribute *tmpfs_attributes[] = { #if IS_ENABLED(CONFIG_UNICODE) - &dev_attr_casefold.attr.attr, + &tmpfs_attr_casefold.attr, #endif NULL }; |