On 4/22/13 8:45 AM, Mark Tinguely wrote: > On 04/21/13 16:55, Eric Sandeen wrote: >> On 4/21/13 12:41 PM, Mark Tinguely wrote: >> >>> This problem happened locally with a bad inode number from xfs >>> recovery. xfs_perag_get() can return NULL if given a bad agno. >>> Most callers of xfs_perag_get() do not check for a NULL before >>> using the pointer. This patch forces a shutdown of the filesystem >>> for those callers that do not check the return value rather than >>> crashing on a dereferenced NULL pointer. >> >> Hi Mark - >> >> I'm curious, what was the callchain when this happened? Was it >> during recovery? If so, would aborting recovery be more prudent? >> >> I might be missing something, but I'm not sure how shutting >> down avoids a subsequent null ptr deref& crash. >> >> i.e. if a caller does something like: >> >> pag = xfs_perag_get(mp, agno); >> spin_lock(&pag->pagb_lock); >> >> shutting down in xfs_perag_get doesn't save us from a >> null pag pointer, would it? >> >> Thanks, >> -Eric > > You are correct, we have to exit the routine(s) to avoid the dereference. Let the callers handle the error. > > Sorry for the noise. No problem, glad I'm useful on the rare occasion. ;) Can you share the backtrace on the null deref you saw? Thanks, -Eric _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
