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commit 2b6d96503255a3ed676cd70f8368870c6d6a25c6 upstream. Fuzzing hit another invalid pointer dereference due to the lack of checking whether jffs2_prealloc_raw_node_refs() completed successfully. Subsequent logic implies that the node refs have been allocated. Handle that. The code is ready for propagating the error upwards. KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] CPU: 1 PID: 5835 Comm: syz-executor145 Not tainted 5.10.234-syzkaller #0 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 RIP: 0010:jffs2_link_node_ref+0xac/0x690 fs/jffs2/nodelist.c:600 Call Trace: jffs2_mark_erased_block fs/jffs2/erase.c:460 [inline] jffs2_erase_pending_blocks+0x688/0x1860 fs/jffs2/erase.c:118 jffs2_garbage_collect_pass+0x638/0x1a00 fs/jffs2/gc.c:253 jffs2_reserve_space+0x3f4/0xad0 fs/jffs2/nodemgmt.c:167 jffs2_write_inode_range+0x246/0xb50 fs/jffs2/write.c:362 jffs2_write_end+0x712/0x1110 fs/jffs2/file.c:302 generic_perform_write+0x2c2/0x500 mm/filemap.c:3347 __generic_file_write_iter+0x252/0x610 mm/filemap.c:3465 generic_file_write_iter+0xdb/0x230 mm/filemap.c:3497 call_write_iter include/linux/fs.h:2039 [inline] do_iter_readv_writev+0x46d/0x750 fs/read_write.c:740 do_iter_write+0x18c/0x710 fs/read_write.c:866 vfs_writev+0x1db/0x6a0 fs/read_write.c:939 do_pwritev fs/read_write.c:1036 [inline] __do_sys_pwritev fs/read_write.c:1083 [inline] __se_sys_pwritev fs/read_write.c:1078 [inline] __x64_sys_pwritev+0x235/0x310 fs/read_write.c:1078 do_syscall_64+0x30/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x67/0xd1 Found by Linux Verification Center (linuxtesting.org) with Syzkaller. Fixes:2f785402f3("[JFFS2] Reduce visibility of raw_node_ref to upper layers of JFFS2 code.") Fixes:f560928baa("[JFFS2] Allocate node_ref for wasted space when skipping to page boundary") Cc: stable@vger.kernel.org Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru> Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com> Signed-off-by: Richard Weinberger <richard@nod.at> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.