Messages in this thread | | | Date | Thu, 24 Dec 2020 00:07:20 +0100 (CET) | From | Richard Weinberger <> | Subject | Re: [PATCH v2] ubifs: Fix read out-of-bounds in ubifs_jnl_write_inode() |
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Chengsong Ke,
----- Ursprüngliche Mail ----- > The memory area allocated in ubifs_jnl_write_inode() is not aligned with 8 > bytes: > ino_start = ino = kmalloc(write_len, GFP_NOFS); > > When ino_start passed into write_head -> ubifs_wbuf_write_nolock: > n = aligned_len >> c->max_write_shift; > if (n) { > n <<= c->max_write_shift; > err = ubifs_leb_write(c, wbuf->lnum, buf + written, wbuf->offs, n); > // Read oob occurs here, read n bytes from buf, and buf is passed from > @ino_start which is > // not 8 bytes aligned(write_len < n). Program read (n - write_len) more bytes. > } > > Reproducer: > 0. config KASAN && apply print.patch > 1. mount ubifs on /root/temp > 2. run test.sh
What does test.sh do?
> 3. cd /root/temp && ls // change atime for link_file > 4. wait 1~2 minutes > > In order to solve the read oob problem in ubifs_wbuf_write_nolock, just align > the write_len to > 8 bytes when alloc the memory. So that this patch will not affect the use of > write_len in other > functions, such as ubifs_jnl_write_inode->make_reservation and > ubifs_jnl_write_inode->ubifs_node_calc_hash.
I gave this a second thought and I'm not so sure anymore what exactly is going on. The problem is real, I fully agree with you but I need to dig deeper into the journal and wbuf code to double check that we really fix the right thing and not just paper other something.
Thanks, //richard
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