6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Baokun Li <libaokun1@xxxxxxxxxx> [ Upstream commit 85b08b31a22b481ec6528130daf94eee4452e23f ] Export fscache_put_volume() and add fscache_try_get_volume() helper function to allow cachefiles to get/put fscache_volume via linux/fscache-cache.h. Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx> Link: https://lore.kernel.org/r/20240628062930.2467993-2-libaokun@xxxxxxxxxxxxxxx Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx> Stable-dep-of: 522018a0de6b ("cachefiles: fix slab-use-after-free in fscache_withdraw_volume()") Stable-dep-of: 5d8f80578907 ("cachefiles: fix slab-use-after-free in cachefiles_withdraw_cookie()") Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/fscache/internal.h | 2 -- fs/fscache/volume.c | 14 ++++++++++++++ include/linux/fscache-cache.h | 6 ++++++ 3 files changed, 20 insertions(+), 2 deletions(-) --- a/fs/fscache/internal.h +++ b/fs/fscache/internal.h @@ -145,8 +145,6 @@ extern const struct seq_operations fscac struct fscache_volume *fscache_get_volume(struct fscache_volume *volume, enum fscache_volume_trace where); -void fscache_put_volume(struct fscache_volume *volume, - enum fscache_volume_trace where); bool fscache_begin_volume_access(struct fscache_volume *volume, struct fscache_cookie *cookie, enum fscache_access_trace why); --- a/fs/fscache/volume.c +++ b/fs/fscache/volume.c @@ -27,6 +27,19 @@ struct fscache_volume *fscache_get_volum return volume; } +struct fscache_volume *fscache_try_get_volume(struct fscache_volume *volume, + enum fscache_volume_trace where) +{ + int ref; + + if (!__refcount_inc_not_zero(&volume->ref, &ref)) + return NULL; + + trace_fscache_volume(volume->debug_id, ref + 1, where); + return volume; +} +EXPORT_SYMBOL(fscache_try_get_volume); + static void fscache_see_volume(struct fscache_volume *volume, enum fscache_volume_trace where) { @@ -420,6 +433,7 @@ void fscache_put_volume(struct fscache_v fscache_free_volume(volume); } } +EXPORT_SYMBOL(fscache_put_volume); /* * Relinquish a volume representation cookie. --- a/include/linux/fscache-cache.h +++ b/include/linux/fscache-cache.h @@ -19,6 +19,7 @@ enum fscache_cache_trace; enum fscache_cookie_trace; enum fscache_access_trace; +enum fscache_volume_trace; enum fscache_cache_state { FSCACHE_CACHE_IS_NOT_PRESENT, /* No cache is present for this name */ @@ -97,6 +98,11 @@ extern void fscache_withdraw_cookie(stru extern void fscache_io_error(struct fscache_cache *cache); +extern struct fscache_volume * +fscache_try_get_volume(struct fscache_volume *volume, + enum fscache_volume_trace where); +extern void fscache_put_volume(struct fscache_volume *volume, + enum fscache_volume_trace where); extern void fscache_end_volume_access(struct fscache_volume *volume, struct fscache_cookie *cookie, enum fscache_access_trace why);
