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f2fs: fix NULL pointer dereference in f2fs_write_begin() 

BUG: kernel NULL pointer dereference, address: 0000000000000000
RIP: 0010:f2fs_write_begin+0x823/0xb90 [f2fs]
Call Trace:
 f2fs_quota_write+0x139/0x1d0 [f2fs]
 write_blk+0x36/0x80 [quota_tree]
 get_free_dqblk+0x42/0xa0 [quota_tree]
 do_insert_tree+0x235/0x4a0 [quota_tree]
 do_insert_tree+0x26e/0x4a0 [quota_tree]
 do_insert_tree+0x26e/0x4a0 [quota_tree]
 do_insert_tree+0x26e/0x4a0 [quota_tree]
 qtree_write_dquot+0x70/0x190 [quota_tree]
 v2_write_dquot+0x43/0x90 [quota_v2]
 dquot_acquire+0x77/0x100
 f2fs_dquot_acquire+0x2f/0x60 [f2fs]
 dqget+0x310/0x450
 dquot_transfer+0x7e/0x120
 f2fs_setattr+0x11a/0x4a0 [f2fs]
 notify_change+0x349/0x480
 chown_common+0x168/0x1c0
 do_fchownat+0xbc/0xf0
 __x64_sys_fchownat+0x20/0x30
 do_syscall_64+0x5f/0x220
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Passing fsdata parameter to .write_{begin,end} in f2fs_quota_write(),
so that if quota file is compressed one, we can avoid above NULL
pointer dereference when updating quota content.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
alistair/sensors
Chao Yu 2020-03-19 19:58:00 +08:00 committed by Jaegeuk Kim
parent 8c7d4b5760
commit 62f63eea29
1 changed files with 3 additions and 2 deletions
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5
fs/f2fs/super.c
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@ -1929,6 +1929,7 @@ static ssize_t f2fs_quota_write(struct super_block *sb, int type,
int offset = off & (sb->s_blocksize - 1);
size_t towrite = len;
struct page *page;
void *fsdata = NULL;
char *kaddr;
int err = 0;
int tocopy;
@ -1938,7 +1939,7 @@ static ssize_t f2fs_quota_write(struct super_block *sb, int type,
towrite);
retry:
err = a_ops->write_begin(NULL, mapping, off, tocopy, 0,
&page, NULL);
&page, &fsdata);
if (unlikely(err)) {
if (err == -ENOMEM) {
congestion_wait(BLK_RW_ASYNC,
@ -1955,7 +1956,7 @@ retry:
flush_dcache_page(page);
a_ops->write_end(NULL, mapping, off, tocopy, tocopy,
page, NULL);
page, fsdata);
offset = 0;
towrite -= tocopy;
off += tocopy;