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    SubjectRe: [PATCH 053/190] Revert "ecryptfs: replace BUG_ON with error handling code"
    On Wed, Apr 21, 2021 at 11:13:29AM -0500, Tyler Hicks wrote:
    > On 2021-04-21 16:04:02, Al Viro wrote:
    > > On Wed, Apr 21, 2021 at 02:58:48PM +0200, Greg Kroah-Hartman wrote:
    > > > This reverts commit 2c2a7552dd6465e8fde6bc9cccf8d66ed1c1eb72.
    > > >
    > > > Commits from @umn.edu addresses have been found to be submitted in "bad
    > > > faith" to try to test the kernel community's ability to review "known
    > > > malicious" changes. The result of these submissions can be found in a
    > > > paper published at the 42nd IEEE Symposium on Security and Privacy
    > > > entitled, "Open Source Insecurity: Stealthily Introducing
    > > > Vulnerabilities via Hypocrite Commits" written by Qiushi Wu (University
    > > > of Minnesota) and Kangjie Lu (University of Minnesota).
    > > >
    > > > Because of this, all submissions from this group must be reverted from
    > > > the kernel tree and will need to be re-reviewed again to determine if
    > > > they actually are a valid fix. Until that work is complete, remove this
    > > > change to ensure that no problems are being introduced into the
    > > > codebase.
    > >
    > > FWIW, commit message on the original (
    > > ecryptfs: replace BUG_ON with error handling code
    > >
    > > In crypt_scatterlist, if the crypt_stat argument is not set up
    > > correctly, the kernel crashes. Instead, by returning an error code
    > > upstream, the error is handled safely.
    > >
    > > The issue is detected via a static analysis tool written by us.
    > >
    > > Fixes: 237fead619984 (ecryptfs: fs/Makefile and fs/Kconfig)
    > > Signed-off-by: Aditya Pakki <pakki001@umn.edu>
    > > Signed-off-by: Tyler Hicks <code@tyhicks.com>
    > > )
    > > really stinks. First, the analysis: condition being tested is
    > > (!crypt_stat || !crypt_stat->tfm
    > > || !(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED))
    > > and their patch replaces BUG_ON() with return of -EINVAL. So the
    > > only thing their tool had detected the presence of BUG_ON().
    > > Was it grep, by any chance?
    > >
    > > IOW, the commit message is "we'd found BUG_ON(); let's replace it
    > > with returning some error value and hope everything works. Whaddya
    > > mean, how do we know? Our tool [git grep BUG_ON, that is] says
    > > it's there and look, it *is* there, so if it's ever reached there'll
    > > be trouble. What, assertion that returning an error will be handled
    > > safely? 'Cuz we saiz so, that's why"
    > >
    > >
    > > It *is* functionally harmless, AFAICS, but only because the condition
    > > is really impossible. However,
    > > * it refers to vague (s)tool they'd produced, nevermind that
    > > all they really do is "find BUG_ON(), replace with returning an error".
    > > * unlike BUG_ON(), the replacement does *NOT* document the
    > > fact that condition should be impossible.
    > > IMO either should be sufficient for rejecting the patch.
    >
    > I agree that it was not a malicious change. There are other places
    > within the same function that return -EINVAL and the expectation is that
    > errors from this function should be handled safely.
    >
    > That said, I can find no real-world reports of this BUG_ON() ever being
    > a problem and I don't think that there's any actual need for this
    > change. So, I'm alright with it being reverted considering the
    > circumstances.
    >
    > Acked-by: Tyler Hicks <code@tyhicks.com>

    Thanks for the review, I've update the commit log message and added your
    ack here.

    greg k-h

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