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authorJan Harkes <jaharkes@cs.cmu.edu>2017-09-27 15:52:12 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-11-24 08:30:05 +0100
commitd73b3941f58ef10d3dbd9de148c5f534ce6bb0fd (patch)
treebd42b1de7efeb357589019818f73522856e6a8cc
parent2722def0f5274f4ccd8a768736158bb297c5feee (diff)
coda: fix 'kernel memory exposure attempt' in fsync
commit d337b66a4c52c7b04eec661d86c2ef6e168965a2 upstream. When an application called fsync on a file in Coda a small request with just the file identifier was allocated, but the declared length was set to the size of union of all possible upcall requests. This bug has been around for a very long time and is now caught by the extra checking in usercopy that was introduced in Linux-4.8. The exposure happens when the Coda cache manager process reads the fsync upcall request at which point it is killed. As a result there is nobody servicing any further upcalls, trapping any processes that try to access the mounted Coda filesystem. Signed-off-by: Jan Harkes <jaharkes@cs.cmu.edu> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--fs/coda/upcall.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/fs/coda/upcall.c b/fs/coda/upcall.c
index 5bb6e27298a4..21dbff85829a 100644
--- a/fs/coda/upcall.c
+++ b/fs/coda/upcall.c
@@ -446,8 +446,7 @@ int venus_fsync(struct super_block *sb, struct CodaFid *fid)
UPARG(CODA_FSYNC);
inp->coda_fsync.VFid = *fid;
- error = coda_upcall(coda_vcp(sb), sizeof(union inputArgs),
- &outsize, inp);
+ error = coda_upcall(coda_vcp(sb), insize, &outsize, inp);
CODA_FREE(inp, insize);
return error;