Re: [PATCH net v3] drivers/net/bonding: Fix out-of-bounds read in bond_option_arp_ip_targets_set()

[Simon Horman <horms@kernel.org>]

On Thu, Apr 18, 2024 at 09:10:23PM +0100, Simon Horman wrote:
> On Wed, Apr 17, 2024 at 02:34:49PM +0800, Sam Sun wrote:
> > On Tue, Apr 16, 2024 at 10:24 PM Simon Horman <horms@kernel.org> wrote:
> > >
> > > On Tue, Apr 16, 2024 at 08:09:44PM +0800, Sam Sun wrote:
> > > > In function bond_option_arp_ip_targets_set(), if newval->string is an
> > > > empty string, newval->string+1 will point to the byte after the
> > > > string, causing an out-of-bound read.
> > > >
> > > > BUG: KASAN: slab-out-of-bounds in strlen+0x7d/0xa0 lib/string.c:418
> > > > Read of size 1 at addr ffff8881119c4781 by task syz-executor665/8107
> > > > CPU: 1 PID: 8107 Comm: syz-executor665 Not tainted 6.7.0-rc7 #1
> > > > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
> > > > Call Trace:
> > > >  <TASK>
> > > >  __dump_stack lib/dump_stack.c:88 [inline]
> > > >  dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
> > > >  print_address_description mm/kasan/report.c:364 [inline]
> > > >  print_report+0xc1/0x5e0 mm/kasan/report.c:475
> > > >  kasan_report+0xbe/0xf0 mm/kasan/report.c:588
> > > >  strlen+0x7d/0xa0 lib/string.c:418
> > > >  __fortify_strlen include/linux/fortify-string.h:210 [inline]
> > > >  in4_pton+0xa3/0x3f0 net/core/utils.c:130
> > > >  bond_option_arp_ip_targets_set+0xc2/0x910
> > > > drivers/net/bonding/bond_options.c:1201
> > > >  __bond_opt_set+0x2a4/0x1030 drivers/net/bonding/bond_options.c:767
> > > >  __bond_opt_set_notify+0x48/0x150 drivers/net/bonding/bond_options.c:792
> > > >  bond_opt_tryset_rtnl+0xda/0x160 drivers/net/bonding/bond_options.c:817
> > > >  bonding_sysfs_store_option+0xa1/0x120 drivers/net/bonding/bond_sysfs.c:156
> > > >  dev_attr_store+0x54/0x80 drivers/base/core.c:2366
> > > >  sysfs_kf_write+0x114/0x170 fs/sysfs/file.c:136
> > > >  kernfs_fop_write_iter+0x337/0x500 fs/kernfs/file.c:334
> > > >  call_write_iter include/linux/fs.h:2020 [inline]
> > > >  new_sync_write fs/read_write.c:491 [inline]
> > > >  vfs_write+0x96a/0xd80 fs/read_write.c:584
> > > >  ksys_write+0x122/0x250 fs/read_write.c:637
> > > >  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
> > > >  do_syscall_64+0x40/0x110 arch/x86/entry/common.c:83
> > > >  entry_SYSCALL_64_after_hwframe+0x63/0x6b
> > > > ---[ end trace ]---
> > > >
> > > > Fix it by adding a check of string length before using it.
> > > >
> > > > v2
> > > > According to Jay and Hangbin's opinion, remove target address in
> > > > netdev_err message since target is not initialized in error path and
> > > > will not provide useful information.
> > > >
> > > > v3
> > > > According to Hangbin's opinion, change Fixes tag from 4fb0ef585eb2
> > > > ("bonding: convert arp_ip_target to use the new option API") to
> > > > f9de11a16594 ("bonding: add ip checks when store ip target").
> > > >
> > > > Fixes: f9de11a16594 ("bonding: add ip checks when store ip target")
> > > > Signed-off-by: Yue Sun <samsun1006219@gmail.com>
> > > > ---
> > >
> > > Hi Sam Sun,
> > >
> > > Some comments about the formatting of this submission:
> > >
> > > * The list of chances, (v2, v3, ...) should be below rather than
> > >   above the scissors ("---"), so it is not included when the patch
> > >   is applied.
> > >
> > > * Looking at git history, the patch prefix should probably be "bonding:"
> > >
> > >         Subject: [PATCH net v3] bonding: ...
> > >
> > > * The diff seems to be a bit mangled, f.e. tabs seem to
> > >   have been translated into spaces. So it does not apply.
> > >   Which breaks automated testing. And for this reason
> > >   I am asking you to repost this patch.
> > >
> > >   git send-email, and b4, are two tools that can typically be used
> > >   to send patches in a way that this doesn't occur.
> > >
> > > ---
> > > pw-bot: changes-requested
> > 
> > I sincerely apologize for not using git send-email. I tried to set up
> > the environment but it did not work. For some reason, I needed to use
> > a proxy to connect with my gmail account, but the proxy service
> > provider banned using their proxy to send email through smtp. Maybe I
> > need to rent a VPS and set up a working environment there, but it
> > would take time and I don't know for sure whether the VPS provider
> > would allow me to send email through smtp either.
> > 
> > Could you or anyone please help me submit this patch? Sorry for
> > causing this trouble.
> 
> Sure, happy to help.
> 
> I'll look at doing this tomororw (Friday),
> unless someone else does so beforehand.

I have posted the patch as v4.
The only changes were:
* Correct whitespace problems,
  which I assume were added in transit as discussed above.
* Update the patch prefix to 'bonding:' as described above
* Move the changelog to below the scissors, as described above

- [PATCH net v4] bonding: Fix out-of-bounds read in bond_option_arp_ip_targets_set()
  https://lore.kernel.org/netdev/20240419-bond-oob-v4-1-69dd1a66db20@kernel.org/