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authorJan Harkes <jaharkes@cs.cmu.edu>2017-09-27 22:52:12 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-11-24 10:35:59 +0300
commit7336a443393f6990749d68052d2b224438605342 (patch)
tree97615c45c1de961e2728a4c5374c6d7839b15eb9
parent26a7acf37b063fd8ffefef7e9203135f0612ce54 (diff)
downloadlinux-7336a443393f6990749d68052d2b224438605342.tar.xz
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 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;