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    SubjectRe: [PATCH 21/24] PM: hibernate: don't use early_lookup_bdev in resume_store
    On Tue, May 23, 2023 at 9:46 AM Christoph Hellwig <hch@lst.de> wrote:
    >
    > resume_store is a sysfs attribute written during normal kernel runtime,
    > and it should not use the early_lookup_bdev API that bypasses all normal
    > path based permission checking, and might cause problems with certain
    > container environments renaming devices.
    >
    > Switch to lookup_bdev, which does a normal path lookup instead, and fall
    > back to trying to parse a numeric dev_t just like early_lookup_bdev did.
    >
    > Note that this strictly speaking changes the kernel ABI as the PARTUUID=
    > and PARTLABEL= style syntax is now not available during a running
    > systems. They never were intended for that, but this breaks things
    > we'll have to figure out a way to make them available again. But if
    > avoidable in any way I'd rather avoid that.
    >
    > Signed-off-by: Christoph Hellwig <hch@lst.de>
    > Fixes: 421a5fa1a6cf ("PM / hibernate: use name_to_dev_t to parse resume")

    Acked-by: Rafael J. Wysocki <rafael@kernel.org>

    > ---
    > kernel/power/hibernate.c | 18 +++++++++++++++++-
    > 1 file changed, 17 insertions(+), 1 deletion(-)
    >
    > diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
    > index c52dedb9f7c8e8..7ae95ec72f9902 100644
    > --- a/kernel/power/hibernate.c
    > +++ b/kernel/power/hibernate.c
    > @@ -1178,7 +1178,23 @@ static ssize_t resume_store(struct kobject *kobj, struct kobj_attribute *attr,
    > if (!name)
    > return -ENOMEM;
    >
    > - error = early_lookup_bdev(name, &dev);
    > + error = lookup_bdev(name, &dev);
    > + if (error) {
    > + unsigned maj, min, offset;
    > + char *p, dummy;
    > +
    > + if (sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2 ||
    > + sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset,
    > + &dummy) == 3) {
    > + dev = MKDEV(maj, min);
    > + if (maj != MAJOR(dev) || min != MINOR(dev))
    > + error = -EINVAL;
    > + } else {
    > + dev = new_decode_dev(simple_strtoul(name, &p, 16));
    > + if (*p)
    > + error = -EINVAL;
    > + }
    > + }
    > kfree(name);
    > if (error)
    > return error;
    > --
    > 2.39.2
    >

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