Messages in this thread | | | Date | Wed, 21 Apr 2021 16:04:02 +0000 | From | Al Viro <> | Subject | Re: [PATCH 053/190] Revert "ecryptfs: replace BUG_ON with error handling code" |
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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.
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