New: size overflow detected in function ext4_mb_new_group_pa
https://bugzilla.kernel.org/show_bug.cgi?id=194695
Bug ID: 194695
Summary: size overflow detected in function
ext4_mb_new_group_pa
Product: File System
Version: 2.5
Kernel Version: 4.9.10-1+grsec201702162016+1
Hardware: x86-64
OS: Linux
Tree: Mainline
Status: NEW
Severity: normal
Priority: P1
Component: ext4
Assignee: [email protected]
Reporter: [email protected]
Regression: NoI am trying to run a kernel with grsecurity with the size overflow protection and am getting the following warnings / errors:
dmesg: http://pastebin.com/wr3UGLS9
config: http://pastebin.com/sr8M9bP0
mballoc.* (make fs/ext4/mballoc.o EXTRA_CFLAGS="-fdump-tree-all -fdump-ipa-all") http://filebin.ca/3DMIChVw9lQM/mballoc.tgz
According to the grsecurity developers it seems to be a bug in ext4, see for some background here:
https://forums.grsecurity.net/viewtopic.php?f=1&t=4678&p=16971
The response from ephox (PAX team / grsecurity developer):
--
Thanks for the report. I think this is an upstream bug. Based on the runtime values provided by you, ext4_mb_new_group_pa() tries to store a value into pa->pa_lstart which larger than UINT_MAX which comes from ext4_group_first_block_no().
Could you please report it to the ext4 developers?
--
I'll try to answer all the questions but I'm not an expert in this area.
Signature · 2 lines
You are receiving this mail because: You are watching the assignee of the bug.
[Bug 194695] size overflow detected in function ext4_mb_new_group_pa
https://bugzilla.kernel.org/show_bug.cgi?id=194695
Andreas Dilger ([email protected]) changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |adilger.kernelbugzilla@dilg
| |er.ca--- Comment #1 from Andreas Dilger ([email protected]) --- Definitely looks like a real bug in:
pa->pa_pstart = ext4_grp_offs_to_block(sb, &ac->ac_b_ex);
pa->pa_lstart = pa->pa_pstart;pa_pstart is 64-bit, pa_lstart is 32-bit.
Signature · 2 lines
You are receiving this mail because: You are watching the assignee of the bug.
[Bug 194695] size overflow detected in function ext4_mb_new_group_pa
In reply to [email protected]https://bugzilla.kernel.org/show_bug.cgi?id=194695
Theodore Tso ([email protected]) changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |[email protected]
--- Comment #2 from Theodore Tso ([email protected]) ---
I don't think we use the pa_lstart value for group preallocations --- a logical number doesn't really have meaning for group pa's. That being said, the
preallocation code is really quite a mess, and it makes it hard to follow. We
should really look at cleaning it up....
Signature · 2 lines
You are receiving this mail because: You are watching the assignee of the bug.