Messages in this thread Patch in this message | | | From | Andrew Donnellan <> | Subject | [PATCH v3 09/24] powerpc/secvar: Warn when PAGE_SIZE is smaller than max object size | Date | Wed, 18 Jan 2023 17:10:34 +1100 |
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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>
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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 d9352d4be87b..68fb0b857442 100644 --- a/arch/powerpc/kernel/secvar-sysfs.c +++ b/arch/powerpc/kernel/secvar-sysfs.c @@ -217,6 +217,7 @@ static int secvar_sysfs_load_static(void) static int secvar_sysfs_init(void) { + u64 max_size; int rc; if (!secvar_ops) { @@ -266,6 +267,14 @@ 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); -- 2.39.0
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