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powerpc/secvar: Warn when PAGE_SIZE is smaller than max object size

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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@linux.ibm.com>
Signed-off-by: Russell Currey <ruscur@russell.cc>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230210080401.345462-13-ajd@linux.ibm.com
This commit is contained in:
Andrew Donnellan 2023-02-10 19:03:47 +11:00 committed by Michael Ellerman
parent 50a466bf3e
commit 6d64c497a3
1 changed files with 9 additions and 0 deletions
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9
arch/powerpc/kernel/secvar-sysfs.c
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@ -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);