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Wong" , linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, syzbot+97f2c05378c5d68dcb8c@syzkaller.appspotmail.com, Yousef Alhouseen Subject: [PATCH v2] xfs: zero newly allocated btree root space Date: Tue, 30 Jun 2026 12:06:21 +0200 Message-ID: <20260630100621.7173-1-alhouseenyousef@gmail.com> X-Mailer: git-send-email 2.54.0 Precedence: bulk X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit xfs_broot_realloc() preserves the existing in-inode btree root while growing its allocation, but leaves the added bytes uninitialized. The inode log formatter copies if_broot_bytes bytes into the journal, so those bytes reach the log record and its CRC calculation before every location has necessarily been overwritten by btree updates. Request __GFP_ZERO for the initial allocation and every subsequent allocation or reallocation, as required by krealloc() semantics. This keeps stale heap contents out of the filesystem log without a separate memset after each growth. Fixes: 6c1c55ac3c05 ("xfs: refactor the inode fork memory allocation functions") Suggested-by: Darrick J. Wong Reported-by: syzbot+97f2c05378c5d68dcb8c@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=97f2c05378c5d68dcb8c Cc: stable@vger.kernel.org Signed-off-by: Yousef Alhouseen --- Changes in v2: - Use __GFP_ZERO instead of an explicit memset after krealloc(). - Apply __GFP_ZERO consistently across the allocation lifetime. fs/xfs/libxfs/xfs_inode_fork.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c index 606a36526ce2..dc05540fa85b 100644 --- a/fs/xfs/libxfs/xfs_inode_fork.c +++ b/fs/xfs/libxfs/xfs_inode_fork.c @@ -384,7 +384,8 @@ xfs_broot_alloc( ASSERT(ifp->if_broot == NULL); ifp->if_broot = kmalloc(new_size, - GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL); + GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL | + __GFP_ZERO); ifp->if_broot_bytes = new_size; return ifp->if_broot; } @@ -417,7 +418,8 @@ xfs_broot_realloc( if (ifp->if_broot_bytes > 0 && ifp->if_broot_bytes > new_size) { struct xfs_btree_block *old_broot = ifp->if_broot; - ifp->if_broot = kmalloc(new_size, GFP_KERNEL | __GFP_NOFAIL); + ifp->if_broot = kmalloc(new_size, + GFP_KERNEL | __GFP_NOFAIL | __GFP_ZERO); ifp->if_broot_bytes = new_size; memcpy(ifp->if_broot, old_broot, new_size); kfree(old_broot); @@ -429,7 +431,7 @@ xfs_broot_realloc( * object. */ ifp->if_broot = krealloc(ifp->if_broot, new_size, - GFP_KERNEL | __GFP_NOFAIL); + GFP_KERNEL | __GFP_NOFAIL | __GFP_ZERO); ifp->if_broot_bytes = new_size; return ifp->if_broot; } -- 2.54.0