On Tue, Jan 15, 2008 at 10:31:18AM +1100, Neil Brown wrote: > On Monday January 14, [EMAIL PROTECTED] wrote: > > > > > > +static ssize_t failover_unlock_ip(struct file *file, char *buf, size_t > > > size) > > > +{ > > > + __be32 server_ip; > > > + char *fo_path; > > > + char *mesg; > > > + > > > + /* sanity check */ > > > + if (size <= 0) > > > + return -EINVAL; > > > > Not only is size never negative, it's actually an unsigned type here, so > > this is a no-op. > > No, It it equivalent to > if (size == 0) > > which alternative is clearer and more maintainable is debatable. > > > > > > + > > > + if (buf[size-1] == '\n') > > > + buf[size-1] = 0; > > > > The other write methods in this file actually just do > > > > if (buf[size-1] != '\n') > > return -EINVAL; > > and those which don't check for size == 0 are underflowing an array. > That should probably be fixed.
? --b. commit 6685389d610950126f700d25f3d010c7049441c3 Author: J. Bruce Fields <[EMAIL PROTECTED]> Date: Tue Jan 22 17:40:42 2008 -0500 nfsd: more careful input validation in nfsctl write methods Neil Brown points out that we're checking buf[size-1] in a couple places without first checking whether size is zero. Actually, given the implementation of simple_transaction_get(), buf[-1] is zero, so in both of these cases the subsequent check of the value of buf[size-1] will catch this case. But it seems fragile to depend on that, so add explicit checks for this case. Signed-off-by: J. Bruce Fields <[EMAIL PROTECTED]> Cc: Neil Brown <[EMAIL PROTECTED]> diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index 61015cf..9ed2a2b 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -304,6 +304,9 @@ static ssize_t write_filehandle(struct file *file, char *buf, size_t size) struct auth_domain *dom; struct knfsd_fh fh; + if (size == 0) + return -EINVAL; + if (buf[size-1] != '\n') return -EINVAL; buf[size-1] = 0; @@ -663,7 +666,7 @@ static ssize_t write_recoverydir(struct file *file, char *buf, size_t size) char *recdir; int len, status; - if (size > PATH_MAX || buf[size-1] != '\n') + if (size == 0 || size > PATH_MAX || buf[size-1] != '\n') return -EINVAL; buf[size-1] = 0;