From: Steven Whitehouse <swhiteho@redhat.com> To: Jesper Juhl <jj@chaosbits.net> Cc: linux-kernel@vger.kernel.org, cluster-devel@redhat.com Subject: Re: [PATCH] GFS2: Fix mem leak in gfs2_get_acl() Date: Mon, 23 Apr 2012 12:12:55 +0100 [thread overview] Message-ID: <1335179575.2708.28.camel@menhir> (raw) In-Reply-To: <alpine.LNX.2.00.1204212258130.25551@swampdragon.chaosbits.net> Hi, On Sat, 2012-04-21 at 23:00 +0200, Jesper Juhl wrote: > If gfs2_xattr_acl_get() returns 0 - which, as far as I can tell, it > may do independently of having allocated memory for its third argument > ('data' in this case) - then we may leak the memory allocated to data. > I'm not so sure... in gfs2_xattr_acl_get() we have: error = gfs2_ea_find(ip, GFS2_EATYPE_SYS, name, &el); if (error) return error; if (!el.el_ea) goto out; if (!GFS2_EA_DATA_LEN(el.el_ea)) <---- zero length means return without allocating goto out; len = GFS2_EA_DATA_LEN(el.el_ea); data = kmalloc(len, GFP_NOFS); etc. So it looks to me as if we will never have allocated any data unless the length is greater than zero, unless I've missed something? Steve. > This patch initializes 'data' to NULL so that it will be safe to call > kfree() on it even if we do not allocate anything and also makes sure > that we kfree(data) in the 'len == 0' case. > > Signed-off-by: Jesper Juhl <jj@chaosbits.net> > --- > fs/gfs2/acl.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > Note: I have tested that this change compiles. It has seen no other > testing than that. > > diff --git a/fs/gfs2/acl.c b/fs/gfs2/acl.c > index 230eb0f..d254d98 100644 > --- a/fs/gfs2/acl.c > +++ b/fs/gfs2/acl.c > @@ -43,7 +43,7 @@ struct posix_acl *gfs2_get_acl(struct inode *inode, int type) > struct gfs2_inode *ip = GFS2_I(inode); > struct posix_acl *acl; > const char *name; > - char *data; > + char *data = NULL; > int len; > > if (!ip->i_eattr) > @@ -60,8 +60,10 @@ struct posix_acl *gfs2_get_acl(struct inode *inode, int type) > len = gfs2_xattr_acl_get(ip, name, &data); > if (len < 0) > return ERR_PTR(len); > - if (len == 0) > + if (len == 0) { > + kfree(data); > return NULL; > + } > > acl = posix_acl_from_xattr(data, len); > kfree(data); > -- > 1.7.10 > >
WARNING: multiple messages have this Message-ID (diff)
From: Steven Whitehouse <swhiteho@redhat.com> To: cluster-devel.redhat.com Subject: [Cluster-devel] [PATCH] GFS2: Fix mem leak in gfs2_get_acl() Date: Mon, 23 Apr 2012 12:12:55 +0100 [thread overview] Message-ID: <1335179575.2708.28.camel@menhir> (raw) In-Reply-To: <alpine.LNX.2.00.1204212258130.25551@swampdragon.chaosbits.net> Hi, On Sat, 2012-04-21 at 23:00 +0200, Jesper Juhl wrote: > If gfs2_xattr_acl_get() returns 0 - which, as far as I can tell, it > may do independently of having allocated memory for its third argument > ('data' in this case) - then we may leak the memory allocated to data. > I'm not so sure... in gfs2_xattr_acl_get() we have: error = gfs2_ea_find(ip, GFS2_EATYPE_SYS, name, &el); if (error) return error; if (!el.el_ea) goto out; if (!GFS2_EA_DATA_LEN(el.el_ea)) <---- zero length means return without allocating goto out; len = GFS2_EA_DATA_LEN(el.el_ea); data = kmalloc(len, GFP_NOFS); etc. So it looks to me as if we will never have allocated any data unless the length is greater than zero, unless I've missed something? Steve. > This patch initializes 'data' to NULL so that it will be safe to call > kfree() on it even if we do not allocate anything and also makes sure > that we kfree(data) in the 'len == 0' case. > > Signed-off-by: Jesper Juhl <jj@chaosbits.net> > --- > fs/gfs2/acl.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > Note: I have tested that this change compiles. It has seen no other > testing than that. > > diff --git a/fs/gfs2/acl.c b/fs/gfs2/acl.c > index 230eb0f..d254d98 100644 > --- a/fs/gfs2/acl.c > +++ b/fs/gfs2/acl.c > @@ -43,7 +43,7 @@ struct posix_acl *gfs2_get_acl(struct inode *inode, int type) > struct gfs2_inode *ip = GFS2_I(inode); > struct posix_acl *acl; > const char *name; > - char *data; > + char *data = NULL; > int len; > > if (!ip->i_eattr) > @@ -60,8 +60,10 @@ struct posix_acl *gfs2_get_acl(struct inode *inode, int type) > len = gfs2_xattr_acl_get(ip, name, &data); > if (len < 0) > return ERR_PTR(len); > - if (len == 0) > + if (len == 0) { > + kfree(data); > return NULL; > + } > > acl = posix_acl_from_xattr(data, len); > kfree(data); > -- > 1.7.10 > >
next prev parent reply other threads:[~2012-04-23 11:13 UTC|newest] Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-04-21 21:00 [PATCH] GFS2: Fix mem leak in gfs2_get_acl() Jesper Juhl 2012-04-23 11:12 ` Steven Whitehouse [this message] 2012-04-23 11:12 ` [Cluster-devel] " Steven Whitehouse
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=1335179575.2708.28.camel@menhir \ --to=swhiteho@redhat.com \ --cc=cluster-devel@redhat.com \ --cc=jj@chaosbits.net \ --cc=linux-kernel@vger.kernel.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.