[PATCH 5.17 0075/1126] jffs2: fix memory leak in jffs2_scan_medium

Greg Kroah-Hartman
2022-04-05T07:47:51Z

From: Baokun Li <libaokun1@huawei.com>

commit 9cdd3128874f5fe759e2c4e1360ab7fb96a8d1df upstream.

If an error is returned in jffs2_scan_eraseblock() and some memory
has been added to the jffs2_summary *s, we can observe the following
kmemleak report:

--------------------------------------------
unreferenced object 0xffff88812b889c40 (size 64):
comm "mount", pid 692, jiffies 4294838325 (age 34.288s)
hex dump (first 32 bytes):
40 48 b5 14 81 88 ff ff 01 e0 31 00 00 00 50 00 @H........1...P.
00 00 01 00 00 00 01 00 00 00 02 00 00 00 09 08 ................
backtrace:
[<ffffffffae93a3a3>] __kmalloc+0x613/0x910
[<ffffffffaf423b9c>] jffs2_sum_add_dirent_mem+0x5c/0xa0
[<ffffffffb0f3afa8>] jffs2_scan_medium.cold+0x36e5/0x4794
[<ffffffffb0f3dbe1>] jffs2_do_mount_fs.cold+0xa7/0x2267
[<ffffffffaf40acf3>] jffs2_do_fill_super+0x383/0xc30
[<ffffffffaf40c00a>] jffs2_fill_super+0x2ea/0x4c0
[<ffffffffb0315d64>] mtd_get_sb+0x254/0x400
[<ffffffffb0315f5f>] mtd_get_sb_by_nr+0x4f/0xd0
[<ffffffffb0316478>] get_tree_mtd+0x498/0x840
[<ffffffffaf40bd15>] jffs2_get_tree+0x25/0x30
[<ffffffffae9f358d>] vfs_get_tree+0x8d/0x2e0
[<ffffffffaea7a98f>] path_mount+0x50f/0x1e50
[<ffffffffaea7c3d7>] do_mount+0x107/0x130
[<ffffffffaea7c5c5>] __se_sys_mount+0x1c5/0x2f0
[<ffffffffaea7c917>] __x64_sys_mount+0xc7/0x160
[<ffffffffb10142f5>] do_syscall_64+0x45/0x70
unreferenced object 0xffff888114b54840 (size 32):
comm "mount", pid 692, jiffies 4294838325 (age 34.288s)
hex dump (first 32 bytes):
c0 75 b5 14 81 88 ff ff 02 e0 02 00 00 00 02 00 .u..............
00 00 84 00 00 00 44 00 00 00 6b 6b 6b 6b 6b a5 ......D...kkkkk.
backtrace:
[<ffffffffae93be24>] kmem_cache_alloc_trace+0x584/0x880
[<ffffffffaf423b04>] jffs2_sum_add_inode_mem+0x54/0x90
[<ffffffffb0f3bd44>] jffs2_scan_medium.cold+0x4481/0x4794
[...]
unreferenced object 0xffff888114b57280 (size 32):
comm "mount", pid 692, jiffies 4294838393 (age 34.357s)
hex dump (first 32 bytes):
10 d5 6c 11 81 88 ff ff 08 e0 05 00 00 00 01 00 ..l.............
00 00 38 02 00 00 28 00 00 00 6b 6b 6b 6b 6b a5 ..8...(...kkkkk.
backtrace:
[<ffffffffae93be24>] kmem_cache_alloc_trace+0x584/0x880
[<ffffffffaf423c34>] jffs2_sum_add_xattr_mem+0x54/0x90
[<ffffffffb0f3a24f>] jffs2_scan_medium.cold+0x298c/0x4794
[...]
unreferenced object 0xffff8881116cd510 (size 16):
comm "mount", pid 692, jiffies 4294838395 (age 34.355s)
hex dump (first 16 bytes):
00 00 00 00 00 00 00 00 09 e0 60 02 00 00 6b a5 ..........`...k.
backtrace:
[<ffffffffae93be24>] kmem_cache_alloc_trace+0x584/0x880
[<ffffffffaf423cc4>] jffs2_sum_add_xref_mem+0x54/0x90
[<ffffffffb0f3b2e3>] jffs2_scan_medium.cold+0x3a20/0x4794
[...]
--------------------------------------------

Therefore, we should call jffs2_sum_reset_collected(s) on exit to
release the memory added in s. In addition, a new tag "out_buf" is
added to prevent the NULL pointer reference caused by s being NULL.
(thanks to Zhang Yi for this analysis)

Fixes: e631ddba5887 ("[JFFS2] Add erase block summary support (mount time improvement)")
Cc: stable@vger.kernel.org
Co-developed-with: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/jffs2/scan.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/fs/jffs2/scan.c
+++ b/fs/jffs2/scan.c
@@ -136,7 +136,7 @@ int jffs2_scan_medium(struct jffs2_sb_in
if (!s) {
JFFS2_WARNING("Can't allocate memory for summary\n");
ret = -ENOMEM;
- goto out;
+ goto out_buf;
}
}

@@ -275,13 +275,15 @@ int jffs2_scan_medium(struct jffs2_sb_in
}
ret = 0;
out:
+ jffs2_sum_reset_collected(s);
+ kfree(s);
+ out_buf:
if (buf_size)
kfree(flashbuf);
#ifndef __ECOS
else
mtd_unpoint(c->mtd, 0, c->mtd->size);
#endif
- kfree(s);
return ret;
}