Greg Kroah-Hartman 1c9bc0f55e sysfs: clamp show() return value in sysfs_kf_read() ...

[ Upstream commit 454257f6d1 ]

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 <neil@brown.name>
Cc: Tejun Heo <tj@kernel.org>
Fixes: 2b75869bba ("sysfs/kernfs: allow attributes to request write buffer be pre-allocated.")
Assisted-by: gregkh_clanker_t1000
Reviewed-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Link: https://patch.msgid.link/2026052000-drove-unicycle-d61b@gregkh
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

2026-07-24 15:54:35 +02:00

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dir.c

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file.c

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group.c

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Kconfig

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Makefile

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mount.c

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symlink.c

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sysfs.h

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