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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 08:32:25 +0100
commit7b7a1c39e8394d4232714093882b733b3e435c67 (patch)
treec8cd77a9986490791fc88bfb5d22728741aa3725 /fs/coda
parentc1b3703b643f0abce65f10cc7716c9ddc9c0decb (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>
Diffstat (limited to 'fs/coda')
-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 f6c6c8adbc01..7289f0a7670b 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;