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([2405:201:682f:383f:4c70:ff68:1915:e456]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-327f90e22f8sm15320206eec.13.2026.08.23.08.27.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 23 Aug 2026 08:27:05 -0700 (PDT) From: Deepanshu Kartikey To: dwmw2@infradead.org, richard@nod.at Cc: kees@kernel.org, viro@zeniv.linux.org.uk, linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, Deepanshu Kartikey , syzbot+675e84fdf3dde67b4946@syzkaller.appspotmail.com Subject: [PATCH] jffs2: fix double-free of f->target in jffs2_alloc_inode() Date: Sun, 23 Aug 2026 20:56:48 +0530 Message-Id: <20260823152648.23136-1-kartikey406@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit jffs2_alloc_inode() does not initialize f->target before returning the new inode. It is normally cleared later by jffs2_init_inode_info(), called from jffs2_iget(), but that runs only after alloc_inode() has already returned successfully. If inode_init_always() fails in between, alloc_inode() calls ->free_inode() directly on the half-initialized inode. jffs2_free_inode() then does kfree(f->target) on whatever stale value was left in the reused slab object, which can be a pointer that was already freed, causing a double-free. Initialize f->target to NULL in jffs2_alloc_inode() to close this window, and clear it in jffs2_free_inode() after freeing it so a reused or re-freed object can never carry a dangling pointer. Fixes: 4fdcfab5b553 ("jffs2: fix use-after-free on symlink traversal") Reported-by: syzbot+675e84fdf3dde67b4946@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=675e84fdf3dde67b4946 Signed-off-by: Deepanshu Kartikey --- fs/jffs2/super.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/jffs2/super.c b/fs/jffs2/super.c index 81396a092ba8..30d753d4c263 100644 --- a/fs/jffs2/super.c +++ b/fs/jffs2/super.c @@ -42,6 +42,7 @@ static struct inode *jffs2_alloc_inode(struct super_block *sb) f = alloc_inode_sb(sb, jffs2_inode_cachep, GFP_KERNEL); if (!f) return NULL; + f->target = NULL; return &f->vfs_inode; } @@ -50,6 +51,7 @@ static void jffs2_free_inode(struct inode *inode) struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode); kfree(f->target); + f->target = NULL; kmem_cache_free(jffs2_inode_cachep, f); } -- 2.34.1