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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 08:37:05 +0100
commit71d3850bf1e9458ed6a6119abe084e253128dee5 (patch)
tree85728ca1b6ebbeeef759b22a3a1921723fc25c8c
parentcb58b8f8a8d7d874690c7530b320a5c90bf0f471 (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 a37f003530d7..1175a1722411 100644
--- a/fs/coda/upcall.c
+++ b/fs/coda/upcall.c
@@ -447,8 +447,7 @@ 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;