Due to sysfs constraints, when writing to a variable, we can only handle writes of up to PAGE_SIZE. It's possible that the maximum object size is larger than PAGE_SIZE, in which case, print a warning on boot so that the user is aware. Signed-off-by: Andrew Donnellan <ajd@xxxxxxxxxxxxx> Signed-off-by: Russell Currey <ruscur@xxxxxxxxxx> Reviewed-by: Stefan Berger <stefanb@xxxxxxxxxxxxx> --- v3: New patch (ajd) --- arch/powerpc/kernel/secvar-sysfs.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/powerpc/kernel/secvar-sysfs.c b/arch/powerpc/kernel/secvar-sysfs.c index bfb19f22c6ba..6ba23b2bb9da 100644 --- a/arch/powerpc/kernel/secvar-sysfs.c +++ b/arch/powerpc/kernel/secvar-sysfs.c @@ -225,6 +225,7 @@ static int secvar_sysfs_load_static(void) static int secvar_sysfs_init(void) { + u64 max_size; int rc; if (!secvar_ops) { @@ -274,6 +275,14 @@ static int secvar_sysfs_init(void) goto err; } + // Due to sysfs limitations, we will only ever get a write buffer of + // up to 1 page in size. Print a warning if this is potentially going + // to cause problems, so that the user is aware. + secvar_ops->max_size(&max_size); + if (max_size > PAGE_SIZE) + pr_warn_ratelimited("PAGE_SIZE (%lu) is smaller than maximum object size (%llu), writes are limited to PAGE_SIZE\n", + PAGE_SIZE, max_size); + return 0; err: kobject_put(secvar_kobj); -- 2.39.1