* [PATCH] tty/vt: fix a memory leak in con_insert_unipair
@ 2020-08-09 22:14 James Bond
2020-08-10 5:16 ` Jiri Slaby
0 siblings, 1 reply; 4+ messages in thread
From: James Bond @ 2020-08-09 22:14 UTC (permalink / raw)
To: jameslouisebond
Cc: Greg Kroah-Hartman, Jiri Slaby, Andrew Morton, Kees Cook,
Michel Lespinasse, Vlastimil Babka, Denis Efremov, linux-kernel
Syzkaller find a memory leak in con_insert_unipair:
BUG: memory leak
unreferenced object 0xffff88804893d100 (size 256):
comm "syz-executor.3", pid 16154, jiffies 4295043307 (age 2392.340s)
hex dump (first 32 bytes):
80 af 88 4e 80 88 ff ff 00 a8 88 4e 80 88 ff ff ...N.......N....
80 ad 88 4e 80 88 ff ff 00 aa 88 4e 80 88 ff ff ...N.......N....
backtrace:
[<00000000f76ff1de>] kmalloc include/linux/slab.h:555 [inline]
[<00000000f76ff1de>] kmalloc_array include/linux/slab.h:596 [inline]
[<00000000f76ff1de>] con_insert_unipair+0x9e/0x1a0 drivers/tty/vt/consolemap.c:482
[<000000002f1ad7da>] con_set_unimap+0x244/0x2a0 drivers/tty/vt/consolemap.c:595
[<0000000046ccb106>] do_unimap_ioctl drivers/tty/vt/vt_ioctl.c:297 [inline]
[<0000000046ccb106>] vt_ioctl+0x863/0x12f0 drivers/tty/vt/vt_ioctl.c:1018
[<00000000db1577ff>] tty_ioctl+0x4cd/0xa30 drivers/tty/tty_io.c:2656
[<00000000e5cdf5ed>] vfs_ioctl fs/ioctl.c:48 [inline]
[<00000000e5cdf5ed>] ksys_ioctl+0xa6/0xd0 fs/ioctl.c:753
[<00000000fb4aa12c>] __do_sys_ioctl fs/ioctl.c:762 [inline]
[<00000000fb4aa12c>] __se_sys_ioctl fs/ioctl.c:760 [inline]
[<00000000fb4aa12c>] __x64_sys_ioctl+0x1a/0x20 fs/ioctl.c:760
[<00000000f561f260>] do_syscall_64+0x4c/0xe0 arch/x86/entry/common.c:384
[<0000000056206928>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
BUG: leak checking failed
To fix this issue, we need to release the pointer p1 when the call of
the function kmalloc_array fail.
Signed-off-by: James Bond <jameslouisebond@gmail.com>
---
drivers/tty/vt/consolemap.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/vt/consolemap.c b/drivers/tty/vt/consolemap.c
index 5947b54d92be..1e8d06c32ca1 100644
--- a/drivers/tty/vt/consolemap.c
+++ b/drivers/tty/vt/consolemap.c
@@ -489,7 +489,10 @@ con_insert_unipair(struct uni_pagedir *p, u_short unicode, u_short fontpos)
p2 = p1[n = (unicode >> 6) & 0x1f];
if (!p2) {
p2 = p1[n] = kmalloc_array(64, sizeof(u16), GFP_KERNEL);
- if (!p2) return -ENOMEM;
+ if (!p2) {
+ kfree(p1);
+ return -ENOMEM;
+ }
memset(p2, 0xff, 64*sizeof(u16)); /* No glyphs for the characters (yet) */
}
--
2.17.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] tty/vt: fix a memory leak in con_insert_unipair
2020-08-09 22:14 [PATCH] tty/vt: fix a memory leak in con_insert_unipair James Bond
@ 2020-08-10 5:16 ` Jiri Slaby
2020-08-10 7:51 ` Greg Kroah-Hartman
0 siblings, 1 reply; 4+ messages in thread
From: Jiri Slaby @ 2020-08-10 5:16 UTC (permalink / raw)
To: James Bond
Cc: Greg Kroah-Hartman, Andrew Morton, Kees Cook, Michel Lespinasse,
Vlastimil Babka, Denis Efremov, linux-kernel, Ben Hutchings
On 10. 08. 20, 0:14, James Bond wrote:
> Syzkaller find a memory leak in con_insert_unipair:
> BUG: memory leak
> unreferenced object 0xffff88804893d100 (size 256):
> comm "syz-executor.3", pid 16154, jiffies 4295043307 (age 2392.340s)
> hex dump (first 32 bytes):
> 80 af 88 4e 80 88 ff ff 00 a8 88 4e 80 88 ff ff ...N.......N....
> 80 ad 88 4e 80 88 ff ff 00 aa 88 4e 80 88 ff ff ...N.......N....
> backtrace:
> [<00000000f76ff1de>] kmalloc include/linux/slab.h:555 [inline]
> [<00000000f76ff1de>] kmalloc_array include/linux/slab.h:596 [inline]
> [<00000000f76ff1de>] con_insert_unipair+0x9e/0x1a0 drivers/tty/vt/consolemap.c:482
> [<000000002f1ad7da>] con_set_unimap+0x244/0x2a0 drivers/tty/vt/consolemap.c:595
> [<0000000046ccb106>] do_unimap_ioctl drivers/tty/vt/vt_ioctl.c:297 [inline]
> [<0000000046ccb106>] vt_ioctl+0x863/0x12f0 drivers/tty/vt/vt_ioctl.c:1018
> [<00000000db1577ff>] tty_ioctl+0x4cd/0xa30 drivers/tty/tty_io.c:2656
> [<00000000e5cdf5ed>] vfs_ioctl fs/ioctl.c:48 [inline]
> [<00000000e5cdf5ed>] ksys_ioctl+0xa6/0xd0 fs/ioctl.c:753
> [<00000000fb4aa12c>] __do_sys_ioctl fs/ioctl.c:762 [inline]
> [<00000000fb4aa12c>] __se_sys_ioctl fs/ioctl.c:760 [inline]
> [<00000000fb4aa12c>] __x64_sys_ioctl+0x1a/0x20 fs/ioctl.c:760
> [<00000000f561f260>] do_syscall_64+0x4c/0xe0 arch/x86/entry/common.c:384
> [<0000000056206928>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> BUG: leak checking failed
>
> To fix this issue, we need to release the pointer p1 when the call of
> the function kmalloc_array fail.
This reminds me of:
commit 15b3cd8ef46ad1b100e0d3c7e38774f330726820
Author: Ben Hutchings <ben@decadent.org.uk>
Date: Tue Jun 4 19:00:39 2019 +0100
Revert "consolemap: Fix a memory leaking bug in
drivers/tty/vt/consolemap.c"
This reverts commit 84ecc2f6eb1cb12e6d44818f94fa49b50f06e6ac.
So NACK.
Do we have some annotations for this instead?
> Signed-off-by: James Bond <jameslouisebond@gmail.com>
> ---
> drivers/tty/vt/consolemap.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/tty/vt/consolemap.c b/drivers/tty/vt/consolemap.c
> index 5947b54d92be..1e8d06c32ca1 100644
> --- a/drivers/tty/vt/consolemap.c
> +++ b/drivers/tty/vt/consolemap.c
> @@ -489,7 +489,10 @@ con_insert_unipair(struct uni_pagedir *p, u_short unicode, u_short fontpos)
> p2 = p1[n = (unicode >> 6) & 0x1f];
> if (!p2) {
> p2 = p1[n] = kmalloc_array(64, sizeof(u16), GFP_KERNEL);
> - if (!p2) return -ENOMEM;
> + if (!p2) {
> + kfree(p1);
> + return -ENOMEM;
> + }
> memset(p2, 0xff, 64*sizeof(u16)); /* No glyphs for the characters (yet) */
> }
thanks,
--
js
suse labs
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] tty/vt: fix a memory leak in con_insert_unipair
2020-08-10 5:16 ` Jiri Slaby
@ 2020-08-10 7:51 ` Greg Kroah-Hartman
2020-08-10 8:14 ` Jiri Slaby
0 siblings, 1 reply; 4+ messages in thread
From: Greg Kroah-Hartman @ 2020-08-10 7:51 UTC (permalink / raw)
To: Jiri Slaby, James Bond
Cc: Andrew Morton, Kees Cook, Michel Lespinasse, Vlastimil Babka,
Denis Efremov, linux-kernel, Ben Hutchings
On Mon, Aug 10, 2020 at 07:16:48AM +0200, Jiri Slaby wrote:
> On 10. 08. 20, 0:14, James Bond wrote:
> > Syzkaller find a memory leak in con_insert_unipair:
> > BUG: memory leak
> > unreferenced object 0xffff88804893d100 (size 256):
> > comm "syz-executor.3", pid 16154, jiffies 4295043307 (age 2392.340s)
> > hex dump (first 32 bytes):
> > 80 af 88 4e 80 88 ff ff 00 a8 88 4e 80 88 ff ff ...N.......N....
> > 80 ad 88 4e 80 88 ff ff 00 aa 88 4e 80 88 ff ff ...N.......N....
> > backtrace:
> > [<00000000f76ff1de>] kmalloc include/linux/slab.h:555 [inline]
> > [<00000000f76ff1de>] kmalloc_array include/linux/slab.h:596 [inline]
> > [<00000000f76ff1de>] con_insert_unipair+0x9e/0x1a0 drivers/tty/vt/consolemap.c:482
> > [<000000002f1ad7da>] con_set_unimap+0x244/0x2a0 drivers/tty/vt/consolemap.c:595
> > [<0000000046ccb106>] do_unimap_ioctl drivers/tty/vt/vt_ioctl.c:297 [inline]
> > [<0000000046ccb106>] vt_ioctl+0x863/0x12f0 drivers/tty/vt/vt_ioctl.c:1018
> > [<00000000db1577ff>] tty_ioctl+0x4cd/0xa30 drivers/tty/tty_io.c:2656
> > [<00000000e5cdf5ed>] vfs_ioctl fs/ioctl.c:48 [inline]
> > [<00000000e5cdf5ed>] ksys_ioctl+0xa6/0xd0 fs/ioctl.c:753
> > [<00000000fb4aa12c>] __do_sys_ioctl fs/ioctl.c:762 [inline]
> > [<00000000fb4aa12c>] __se_sys_ioctl fs/ioctl.c:760 [inline]
> > [<00000000fb4aa12c>] __x64_sys_ioctl+0x1a/0x20 fs/ioctl.c:760
> > [<00000000f561f260>] do_syscall_64+0x4c/0xe0 arch/x86/entry/common.c:384
> > [<0000000056206928>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> > BUG: leak checking failed
> >
> > To fix this issue, we need to release the pointer p1 when the call of
> > the function kmalloc_array fail.
>
> This reminds me of:
> commit 15b3cd8ef46ad1b100e0d3c7e38774f330726820
> Author: Ben Hutchings <ben@decadent.org.uk>
> Date: Tue Jun 4 19:00:39 2019 +0100
>
> Revert "consolemap: Fix a memory leaking bug in
> drivers/tty/vt/consolemap.c"
>
> This reverts commit 84ecc2f6eb1cb12e6d44818f94fa49b50f06e6ac.
>
>
>
> So NACK.
I have a whole talk just about the "fun" involved with that change:
https://kernel-recipes.org/en/2019/talks/cves-are-dead-long-live-the-cve/
> Do we have some annotations for this instead?
We need something there, a comment saying "this is fine, don't touch
it!" or something like that? We need that in a few other places in the
vt code as well.
> > Signed-off-by: James Bond <jameslouisebond@gmail.com>
Nice name...
James, can you mark this syzbot report as "invalid" or something like
that please so that this does not come up again and again.
thanks,
greg k-h
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] tty/vt: fix a memory leak in con_insert_unipair
2020-08-10 7:51 ` Greg Kroah-Hartman
@ 2020-08-10 8:14 ` Jiri Slaby
0 siblings, 0 replies; 4+ messages in thread
From: Jiri Slaby @ 2020-08-10 8:14 UTC (permalink / raw)
To: Greg Kroah-Hartman, James Bond
Cc: Andrew Morton, Kees Cook, Michel Lespinasse, Vlastimil Babka,
Denis Efremov, linux-kernel, Ben Hutchings
On 10. 08. 20, 9:51, Greg Kroah-Hartman wrote:
> On Mon, Aug 10, 2020 at 07:16:48AM +0200, Jiri Slaby wrote:
>> On 10. 08. 20, 0:14, James Bond wrote:
>>> Syzkaller find a memory leak in con_insert_unipair:
>>> BUG: memory leak
>>> unreferenced object 0xffff88804893d100 (size 256):
>>> comm "syz-executor.3", pid 16154, jiffies 4295043307 (age 2392.340s)
>>> hex dump (first 32 bytes):
>>> 80 af 88 4e 80 88 ff ff 00 a8 88 4e 80 88 ff ff ...N.......N....
>>> 80 ad 88 4e 80 88 ff ff 00 aa 88 4e 80 88 ff ff ...N.......N....
>>> backtrace:
>>> [<00000000f76ff1de>] kmalloc include/linux/slab.h:555 [inline]
>>> [<00000000f76ff1de>] kmalloc_array include/linux/slab.h:596 [inline]
>>> [<00000000f76ff1de>] con_insert_unipair+0x9e/0x1a0 drivers/tty/vt/consolemap.c:482
>>> [<000000002f1ad7da>] con_set_unimap+0x244/0x2a0 drivers/tty/vt/consolemap.c:595
>>> [<0000000046ccb106>] do_unimap_ioctl drivers/tty/vt/vt_ioctl.c:297 [inline]
>>> [<0000000046ccb106>] vt_ioctl+0x863/0x12f0 drivers/tty/vt/vt_ioctl.c:1018
>>> [<00000000db1577ff>] tty_ioctl+0x4cd/0xa30 drivers/tty/tty_io.c:2656
>>> [<00000000e5cdf5ed>] vfs_ioctl fs/ioctl.c:48 [inline]
>>> [<00000000e5cdf5ed>] ksys_ioctl+0xa6/0xd0 fs/ioctl.c:753
>>> [<00000000fb4aa12c>] __do_sys_ioctl fs/ioctl.c:762 [inline]
>>> [<00000000fb4aa12c>] __se_sys_ioctl fs/ioctl.c:760 [inline]
>>> [<00000000fb4aa12c>] __x64_sys_ioctl+0x1a/0x20 fs/ioctl.c:760
>>> [<00000000f561f260>] do_syscall_64+0x4c/0xe0 arch/x86/entry/common.c:384
>>> [<0000000056206928>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>> BUG: leak checking failed
>>>
>>> To fix this issue, we need to release the pointer p1 when the call of
>>> the function kmalloc_array fail.
...
>> Do we have some annotations for this instead?
>
> We need something there, a comment saying "this is fine, don't touch
> it!" or something like that? We need that in a few other places in the
> vt code as well.
Sure, comment as the last resort (to silence patch writers). But I had
some kmemleak annotation (to silence the warning) in mind.
Or better fix/tune kmemleak: why it dares to think it's a mem leak in
the first place?
thanks,
--
js
^ permalink raw reply [flat|nested] 4+ messages in thread
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2020-08-09 22:14 [PATCH] tty/vt: fix a memory leak in con_insert_unipair James Bond
2020-08-10 5:16 ` Jiri Slaby
2020-08-10 7:51 ` Greg Kroah-Hartman
2020-08-10 8:14 ` Jiri Slaby
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