From d337b66a4c52c7b04eec661d86c2ef6e168965a2 Mon Sep 17 00:00:00 2001 From: Jan Harkes Date: Wed, 27 Sep 2017 15:52:12 -0400 Subject: coda: fix 'kernel memory exposure attempt' in fsync 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. Cc: stable@vger.kernel.org Signed-off-by: Jan Harkes Signed-off-by: Al Viro --- fs/coda/upcall.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'fs/coda') diff --git a/fs/coda/upcall.c b/fs/coda/upcall.c index e82357c89979..8cf16d8c5261 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; -- cgit v1.2.3