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authorDarrick J. Wong <darrick.wong@oracle.com>2017-04-23 10:45:21 -0700
committerDarrick J. Wong <darrick.wong@oracle.com>2017-04-25 09:40:42 -0700
commit12e4a381c5cefa4bf54547cb51d98241a54e29f3 (patch)
tree517387652728da23c8e267d4160ea42191de2353
parent9d17e14cc052ecebb572d4546c7deeddc0c6e040 (diff)
xfs: fix getfsmap userspace memory corruption while setting OF_LAST
At the end of a getfsmap call, we will set FMR_OF_LAST in the last struct fsmap that was handed in by userspace if we've truly run out of space mapping record (as opposed to simply running out of space in the user array). Unfortunately, fmh_entries is the wrong check for whether or not we've filled out anything in the user array because the ioctl provides that fmh_count==0 sets fmh_entries without filling out the user array. Therefore we end up writing things into user memory areas that we weren't given, and kaboom. Since Christoph amended the getfsmap structure to track the number of fsmap entries we've actually filled out, use that as part of deciding if we have to set the OF_LAST flag. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
-rw-r--r--fs/xfs/xfs_ioctl.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index eee8b0f22d75..6190697603c9 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -1674,7 +1674,7 @@ xfs_ioc_getfsmap(
return error;
/* If we didn't abort, set the "last" flag in the last fmx */
- if (!aborted && xhead.fmh_entries) {
+ if (!aborted && info.idx) {
info.last_flags |= FMR_OF_LAST;
if (copy_to_user(&info.data->fmh_recs[info.idx - 1].fmr_flags,
&info.last_flags, sizeof(info.last_flags)))