On Tue, 6 Sep 2011, Christoph Hellwig wrote: > On Tue, Sep 06, 2011 at 05:29:37PM +0200, Lukas Czerner wrote: > > In xfs_ioc_trim it is possible that start+len might overflow. Fix it by > > decrementing the len so that start+len equals to the file system size in > > the worst case. > > > > Signed-off-by: Lukas Czerner <lczerner@xxxxxxxxxx> > > > @@ -146,6 +146,7 @@ xfs_ioc_trim( > > unsigned int granularity = q->limits.discard_granularity; > > struct fstrim_range range; > > xfs_fsblock_t start, len, minlen; > > + xfs_fsblock_t max_blks = mp->m_sb.sb_dblocks; > > xfs_agnumber_t start_agno, end_agno, agno; > > __uint64_t blocks_trimmed = 0; > > int error, last_error = 0; > > @@ -171,7 +172,8 @@ xfs_ioc_trim( > > start_agno = XFS_FSB_TO_AGNO(mp, start); > > if (start_agno >= mp->m_sb.sb_agcount) > > return -XFS_ERROR(EINVAL); > > - > > + if (len > max_blks) > > + len = max_blks - start; > > Is this really the correct check? > > Shouldn't it be > > if (start + len > max_blks) > len = max_blks - start; > > I'd also just use the mp->m_sb.sb_dblocks value directly instead > of assigning it to a local variable. > Agh, you're right. I am bit too hasty I guess. I thought that if (start_agno >= mp->m_sb.sb_agcount) return -XFS_ERROR(EINVAL); will cover us from the unreasonably big start, however if the file system has really huge number of AGs than it will fail to prevent the overflow, I am not sure if that is possible to happen, but what you proposed is definitely better. Thanks! -Lukas _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
