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Biederman" Cc: Alexey Dobriyan , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: [PATCH v2] proc/sysctl: don't return ENOMEM on lookup when a table is unregistering Message-ID: <20181213232052.GA1513@visor> References: <20181213015742.GA28776@visor> <20181213065826.GL2217@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181213065826.GL2217@ZenIV.linux.org.uk> User-Agent: Mutt/1.11.1 (2018-12-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org proc_sys_lookup can fail with ENOMEM instead of ENOENT when the corresponding sysctl table is being unregistered. In our case we see this upon opening /proc/sys/net/*/conf files while network interfaces are being deleted, which confuses our configuration daemon. The problem was successfully reproduced and this fix tested on v4.9.122 and v4.20-rc6. v2: return ERR_PTRs in all cases when proc_sys_make_inode fails instead of mixing them with NULL. Thanks Al Viro for the feedback. Fixes: ace0c791e6c3 ("proc/sysctl: Don't grab i_lock under sysctl_lock.") Cc: stable@vger.kernel.org Signed-off-by: Ivan Delalande --- fs/proc/proc_sysctl.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c index 89921a0d2ebb..e9d4fc40d832 100644 --- a/fs/proc/proc_sysctl.c +++ b/fs/proc/proc_sysctl.c @@ -464,7 +464,7 @@ static struct inode *proc_sys_make_inode(struct super_block *sb, inode = new_inode(sb); if (!inode) - goto out; + return ERR_PTR(-ENOMEM); inode->i_ino = get_next_ino(); @@ -474,7 +474,7 @@ static struct inode *proc_sys_make_inode(struct super_block *sb, if (unlikely(head->unregistering)) { spin_unlock(&sysctl_lock); iput(inode); - inode = NULL; + inode = ERR_PTR(-ENOENT); goto out; } ei->sysctl = head; @@ -549,10 +549,11 @@ static struct dentry *proc_sys_lookup(struct inode *dir, struct dentry *dentry, goto out; } - err = ERR_PTR(-ENOMEM); inode = proc_sys_make_inode(dir->i_sb, h ? h : head, p); - if (!inode) + if (IS_ERR(inode)) { + err = ERR_CAST(inode); goto out; + } d_set_d_op(dentry, &proc_sys_dentry_operations); err = d_splice_alias(inode, dentry); @@ -685,7 +686,7 @@ static bool proc_sys_fill_cache(struct file *file, if (d_in_lookup(child)) { struct dentry *res; inode = proc_sys_make_inode(dir->d_sb, head, table); - if (!inode) { + if (IS_ERR(inode)) { d_lookup_done(child); dput(child); return false; -- 2.20.0