From c0019b7db1d7ac62c711cda6b357a659d46428fe Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Sun, 14 Nov 2021 15:16:04 -0500 Subject: NFSD: Fix exposure in nfsd4_decode_bitmap() rtm@csail.mit.edu reports: > nfsd4_decode_bitmap4() will write beyond bmval[bmlen-1] if the RPC > directs it to do so. This can cause nfsd4_decode_state_protect4_a() > to write client-supplied data beyond the end of > nfsd4_exchange_id.spo_must_allow[] when called by > nfsd4_decode_exchange_id(). Rewrite the loops so nfsd4_decode_bitmap() cannot iterate beyond @bmlen. Reported by: rtm@csail.mit.edu Fixes: d1c263a031e8 ("NFSD: Replace READ* macros in nfsd4_decode_fattr()") Signed-off-by: Chuck Lever Signed-off-by: J. Bruce Fields --- fs/nfsd/nfs4xdr.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) (limited to 'fs/nfsd') diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c index 9b609aac47e1..5bdfaa43c99d 100644 --- a/fs/nfsd/nfs4xdr.c +++ b/fs/nfsd/nfs4xdr.c @@ -288,11 +288,8 @@ nfsd4_decode_bitmap4(struct nfsd4_compoundargs *argp, u32 *bmval, u32 bmlen) p = xdr_inline_decode(argp->xdr, count << 2); if (!p) return nfserr_bad_xdr; - i = 0; - while (i < count) - bmval[i++] = be32_to_cpup(p++); - while (i < bmlen) - bmval[i++] = 0; + for (i = 0; i < bmlen; i++) + bmval[i] = (i < count) ? be32_to_cpup(p++) : 0; return nfs_ok; } -- cgit v1.2.3