From: Chuck Lever <chuck.lever@xxxxxxxxxx> [ Upstream commit 986a4b63d3bc5f2c0eb4083b05aff2bf883b7b2f ] Braino when converting "buf->len -=" to "buf->len = len -". The result is under-estimation of the ralign and rslack values. On krb5p mounts, this has caused READDIR to fail with EIO, and KASAN splats when decoding READLINK replies. As a result of fixing this oversight, the gss_unwrap method now returns a buf->len that can be shorter than priv_len for small RPC messages. The additional adjustment done in unwrap_priv_data() can underflow buf->len. This causes the nfsd_request_too_large check to fail during some NFSv3 operations. Reported-by: Marian Rainer-Harbach Reported-by: Pierre Sauter <pierre.sauter@xxxxxxx> BugLink: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1886277 Fixes: 31c9590ae468 ("SUNRPC: Add "@len" parameter to gss_unwrap()") Reviewed-by: J. Bruce Fields <bfields@xxxxxxxxxx> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- net/sunrpc/auth_gss/gss_krb5_wrap.c | 2 +- net/sunrpc/auth_gss/svcauth_gss.c | 1 - 2 files changed, 1 insertion(+), 2 deletions(-) diff --git a/net/sunrpc/auth_gss/gss_krb5_wrap.c b/net/sunrpc/auth_gss/gss_krb5_wrap.c index cf0fd170ac189..90b8329fef824 100644 --- a/net/sunrpc/auth_gss/gss_krb5_wrap.c +++ b/net/sunrpc/auth_gss/gss_krb5_wrap.c @@ -584,7 +584,7 @@ gss_unwrap_kerberos_v2(struct krb5_ctx *kctx, int offset, int len, buf->head[0].iov_len); memmove(ptr, ptr + GSS_KRB5_TOK_HDR_LEN + headskip, movelen); buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip; - buf->len = len - GSS_KRB5_TOK_HDR_LEN + headskip; + buf->len = len - (GSS_KRB5_TOK_HDR_LEN + headskip); /* Trim off the trailing "extra count" and checksum blob */ xdr_buf_trim(buf, ec + GSS_KRB5_TOK_HDR_LEN + tailskip); diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c index 46027d0c903f9..c28051f7d217d 100644 --- a/net/sunrpc/auth_gss/svcauth_gss.c +++ b/net/sunrpc/auth_gss/svcauth_gss.c @@ -958,7 +958,6 @@ unwrap_priv_data(struct svc_rqst *rqstp, struct xdr_buf *buf, u32 seq, struct gs maj_stat = gss_unwrap(ctx, 0, priv_len, buf); pad = priv_len - buf->len; - buf->len -= pad; /* The upper layers assume the buffer is aligned on 4-byte boundaries. * In the krb5p case, at least, the data ends up offset, so we need to * move it around. */ -- 2.25.1
