cachefiles: flush all requests after setting CACHEFILES_DEAD
[ Upstream commit 85e833cd7243bda7285492b0653c3abb1e2e757b ] In ondemand mode, when the daemon is processing an open request, if the kernel flags the cache as CACHEFILES_DEAD, the cachefiles_daemon_write() will always return -EIO, so the daemon can't pass the copen to the kernel. Then the kernel process that is waiting for the copen triggers a hung_task. Since the DEAD state is irreversible, it can only be exited by closing /dev/cachefiles. Therefore, after calling cachefiles_io_error() to mark the cache as CACHEFILES_DEAD, if in ondemand mode, flush all requests to avoid the above hungtask. We may still be able to read some of the cached data before closing the fd of /dev/cachefiles. Note that this relies on the patch that adds reference counting to the req, otherwise it may UAF. Fixes: c8383054506c ("cachefiles: notify the user daemon when looking up cookie") Signed-off-by: Baokun Li <libaokun1@huawei.com> Link: https://lore.kernel.org/r/20240522114308.2402121-12-libaokun@huaweicloud.com Acked-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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eac51d9daa
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fs/cachefiles
@ -133,7 +133,7 @@ static int cachefiles_daemon_open(struct inode *inode, struct file *file)
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return 0;
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return 0;
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}
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}
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static void cachefiles_flush_reqs(struct cachefiles_cache *cache)
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void cachefiles_flush_reqs(struct cachefiles_cache *cache)
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{
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{
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struct xarray *xa = &cache->reqs;
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struct xarray *xa = &cache->reqs;
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struct cachefiles_req *req;
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struct cachefiles_req *req;
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@ -188,6 +188,7 @@ extern int cachefiles_has_space(struct cachefiles_cache *cache,
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* daemon.c
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* daemon.c
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*/
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*/
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extern const struct file_operations cachefiles_daemon_fops;
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extern const struct file_operations cachefiles_daemon_fops;
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extern void cachefiles_flush_reqs(struct cachefiles_cache *cache);
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extern void cachefiles_get_unbind_pincount(struct cachefiles_cache *cache);
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extern void cachefiles_get_unbind_pincount(struct cachefiles_cache *cache);
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extern void cachefiles_put_unbind_pincount(struct cachefiles_cache *cache);
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extern void cachefiles_put_unbind_pincount(struct cachefiles_cache *cache);
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@ -414,6 +415,8 @@ do { \
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pr_err("I/O Error: " FMT"\n", ##__VA_ARGS__); \
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pr_err("I/O Error: " FMT"\n", ##__VA_ARGS__); \
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fscache_io_error((___cache)->cache); \
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fscache_io_error((___cache)->cache); \
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set_bit(CACHEFILES_DEAD, &(___cache)->flags); \
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set_bit(CACHEFILES_DEAD, &(___cache)->flags); \
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if (cachefiles_in_ondemand_mode(___cache)) \
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cachefiles_flush_reqs(___cache); \
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} while (0)
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} while (0)
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#define cachefiles_io_error_obj(object, FMT, ...) \
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#define cachefiles_io_error_obj(object, FMT, ...) \
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