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fs: sysfs_emit_at: Remove PAGE_SIZE alignment check
From: Eric Biggers <ebiggers@google.com> [No upstream commit because this fixes a bug in a backport.] Before upstream commit59bb47985c
("mm, sl[aou]b: guarantee natural alignment for kmalloc(power-of-two)") which went into v5.4, kmalloc did *not* always guarantee that PAGE_SIZE allocations are PAGE_SIZE-aligned. Upstream commit2efc459d06
("sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output") added two WARN()s that trigger when PAGE_SIZE allocations are not PAGE_SIZE-aligned. This was backported to old kernels that don't guarantee PAGE_SIZE alignment. Commit10ddfb4952
("fs: sysfs_emit: Remove PAGE_SIZE alignment check") in 4.19.y, and its equivalent in 4.14.y and 4.9.y, tried to fix this bug. However, only it handled sysfs_emit(), not sysfs_emit_at(). Fix it in sysfs_emit_at() too. A reproducer is to build the kernel with the following options: CONFIG_SLUB=y CONFIG_SLUB_DEBUG=y CONFIG_SLUB_DEBUG_ON=y CONFIG_PM=y CONFIG_SUSPEND=y CONFIG_PM_WAKELOCKS=y Then run: echo foo > /sys/power/wake_lock && cat /sys/power/wake_lock Fixes:cb1f69d53a
("sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output") Reported-by: kernel test robot <yujie.liu@intel.com> Link: https://lore.kernel.org/r/202303141634.1e64fd76-yujie.liu@intel.com Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -592,7 +592,7 @@ int sysfs_emit_at(char *buf, int at, const char *fmt, ...)
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va_list args;
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int len;
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if (WARN(!buf || offset_in_page(buf) || at < 0 || at >= PAGE_SIZE,
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if (WARN(!buf || at < 0 || at >= PAGE_SIZE,
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"invalid sysfs_emit_at: buf:%p at:%d\n", buf, at))
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return 0;
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