6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Fedor Pchelkin pchelkin@ispras.ru
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: 2f785402f39b ("[JFFS2] Reduce visibility of raw_node_ref to upper layers of JFFS2 code.") Fixes: f560928baa60 ("[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 --- fs/jffs2/erase.c | 4 +++- fs/jffs2/scan.c | 4 +++- 2 files changed, 6 insertions(+), 2 deletions(-)
--- a/fs/jffs2/erase.c +++ b/fs/jffs2/erase.c @@ -425,7 +425,9 @@ static void jffs2_mark_erased_block(stru .totlen = cpu_to_je32(c->cleanmarker_size) };
- jffs2_prealloc_raw_node_refs(c, jeb, 1); + ret = jffs2_prealloc_raw_node_refs(c, jeb, 1); + if (ret) + goto filebad;
marker.hdr_crc = cpu_to_je32(crc32(0, &marker, sizeof(struct jffs2_unknown_node)-4));
--- a/fs/jffs2/scan.c +++ b/fs/jffs2/scan.c @@ -256,7 +256,9 @@ int jffs2_scan_medium(struct jffs2_sb_in
jffs2_dbg(1, "%s(): Skipping %d bytes in nextblock to ensure page alignment\n", __func__, skip); - jffs2_prealloc_raw_node_refs(c, c->nextblock, 1); + ret = jffs2_prealloc_raw_node_refs(c, c->nextblock, 1); + if (ret) + goto out; jffs2_scan_dirty_space(c, c->nextblock, skip); } #endif