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Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [PATCH] fs: xfs: add NULL pointer check Content-Language: en-US To: cgel.zte@gmail.com, djwong@kernel.org Cc: linux-xfs@vger.kernel.org, dchinner@redhat.com, chandan.babu@oracle.com, bfoster@redhat.com, allison.henderson@oracle.com, lv.ruyi@zte.com.cn, linux-kernel@vger.kernel.org, Zeal Robot References: <20220328032642.2371596-1-lv.ruyi@zte.com.cn> From: Damien Le Moal Organization: Western Digital Research In-Reply-To: <20220328032642.2371596-1-lv.ruyi@zte.com.cn> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/28/22 12:26, cgel.zte@gmail.com wrote: > From: Lv Ruyi > > kmem_zalloc() is a memory allocation function which can return NULL when > some internal memory errors happen. It is safer to check NULL pointer. > > Reported-by: Zeal Robot > Signed-off-by: Lv Ruyi > --- > fs/xfs/libxfs/xfs_attr_leaf.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c > index 014daa8c542d..e6694f49f563 100644 > --- a/fs/xfs/libxfs/xfs_attr_leaf.c > +++ b/fs/xfs/libxfs/xfs_attr_leaf.c > @@ -1571,6 +1571,8 @@ xfs_attr3_leaf_compact( > trace_xfs_attr_leaf_compact(args); > > tmpbuffer = kmem_alloc(args->geo->blksize, 0); See kmem_alloc() code: this function cannot fail (it retries the allocation until success). So checking for NULL pointer does not make sense. > + if (!tmpbuffer) > + return; > memcpy(tmpbuffer, bp->b_addr, args->geo->blksize); > memset(bp->b_addr, 0, args->geo->blksize); > leaf_src = (xfs_attr_leafblock_t *)tmpbuffer; > @@ -2290,6 +2292,8 @@ xfs_attr3_leaf_unbalance( > struct xfs_attr3_icleaf_hdr tmphdr; > > tmp_leaf = kmem_zalloc(state->args->geo->blksize, 0); > + if (!tmp_leaf) > + return; > > /* > * Copy the header into the temp leaf so that all the stuff -- Damien Le Moal Western Digital Research