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author | David Woodhouse <dwmw2@infradead.org> | 2009-11-30 09:06:40 (GMT) |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-11-30 21:52:40 (GMT) |
commit | 199bc9ff5ca5e4b3bcaff8927b2983c65f34c263 (patch) | |
tree | 65eae0838210e0807e75ed2caa7e1f2d151b7f09 | |
parent | c69f677cc852f3f7b2342ab2f1598670a463d576 (diff) | |
download | linux-fsl-qoriq-199bc9ff5ca5e4b3bcaff8927b2983c65f34c263.tar.xz |
jffs2: Fix memory corruption in jffs2_read_inode_range()
In 2.6.23 kernel, commit a32ea1e1f925399e0d81ca3f7394a44a6dafa12c
("Fix read/truncate race") fixed a race in the generic code, and as a
side effect, now do_generic_file_read() can ask us to readpage() past
the i_size. This seems to be correctly handled by the block routines
(e.g. block_read_full_page() fills the page with zeroes in case if
somebody is trying to read past the last inode's block).
JFFS2 doesn't handle this; it assumes that it won't be asked to read
pages which don't exist -- and thus that there will be at least _one_
valid 'frag' on the page it's being asked to read. It will fill any
holes with the following memset:
memset(buf, 0, min(end, frag->ofs + frag->size) - offset);
When the 'closest smaller match' returned by jffs2_lookup_node_frag() is
actually on a previous page and ends before 'offset', that results in:
memset(buf, 0, <huge unsigned negative>);
Hopefully, in most cases the corruption is fatal, and quickly causing
random oopses, like this:
root@10.0.0.4:~/ltp-fs-20090531# ./testcases/kernel/fs/ftest/ftest01
Unable to handle kernel paging request for data at address 0x00000008
Faulting instruction address: 0xc01cd980
Oops: Kernel access of bad area, sig: 11 [#1]
[...]
NIP [c01cd980] rb_insert_color+0x38/0x184
LR [c0043978] enqueue_hrtimer+0x88/0xc4
Call Trace:
[c6c63b60] [c004f9a8] tick_sched_timer+0xa0/0xe4 (unreliable)
[c6c63b80] [c0043978] enqueue_hrtimer+0x88/0xc4
[c6c63b90] [c0043a48] __run_hrtimer+0x94/0xbc
[c6c63bb0] [c0044628] hrtimer_interrupt+0x140/0x2b8
[c6c63c10] [c000f8e8] timer_interrupt+0x13c/0x254
[c6c63c30] [c001352c] ret_from_except+0x0/0x14
--- Exception: 901 at memset+0x38/0x5c
LR = jffs2_read_inode_range+0x144/0x17c
[c6c63cf0] [00000000] (null) (unreliable)
This patch fixes the issue, plus fixes all LTP tests on NAND/UBI with
JFFS2 filesystem that were failing since 2.6.23 (seems like the bug
above also broke the truncation).
Reported-By: Anton Vorontsov <avorontsov@ru.mvista.com>
Tested-By: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r-- | fs/jffs2/read.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/fs/jffs2/read.c b/fs/jffs2/read.c index cfe05c1..3f39be1 100644 --- a/fs/jffs2/read.c +++ b/fs/jffs2/read.c @@ -164,12 +164,15 @@ int jffs2_read_inode_range(struct jffs2_sb_info *c, struct jffs2_inode_info *f, /* XXX FIXME: Where a single physical node actually shows up in two frags, we read it twice. Don't do that. */ - /* Now we're pointing at the first frag which overlaps our page */ + /* Now we're pointing at the first frag which overlaps our page + * (or perhaps is before it, if we've been asked to read off the + * end of the file). */ while(offset < end) { D2(printk(KERN_DEBUG "jffs2_read_inode_range: offset %d, end %d\n", offset, end)); - if (unlikely(!frag || frag->ofs > offset)) { + if (unlikely(!frag || frag->ofs > offset || + frag->ofs + frag->size <= offset)) { uint32_t holesize = end - offset; - if (frag) { + if (frag && frag->ofs > offset) { D1(printk(KERN_NOTICE "Eep. Hole in ino #%u fraglist. frag->ofs = 0x%08x, offset = 0x%08x\n", f->inocache->ino, frag->ofs, offset)); holesize = min(holesize, frag->ofs - offset); } |