4.9-stable review patch. If anyone has any objections, please let me know.
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From: Jan Harkes jaharkes@cs.cmu.edu
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
--- fs/coda/upcall.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
--- a/fs/coda/upcall.c +++ b/fs/coda/upcall.c @@ -446,8 +446,7 @@ int venus_fsync(struct super_block *sb, 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;