* [PATCH] tty: fix when iov_iter_count() returns 0 in tty_write()
@ 2021-02-17 14:43 Sabyrzhan Tasbolatov
2021-02-17 15:13 ` Greg KH
0 siblings, 1 reply; 5+ messages in thread
From: Sabyrzhan Tasbolatov @ 2021-02-17 14:43 UTC (permalink / raw)
To: gregkh, jirislaby; +Cc: linux-kernel, syzbot+3d2c27c2b7dc2a94814d
syzbot found WARNING in iov_iter_revert[1] when iov_iter_count() returns 0,
therefore INT_MAX is passed to iov_iter_revert() causing > MAX_RW_COUNT
warning.
static inline ssize_t do_tty_write()
{
..
size_t count = iov_iter_count(from);
..
size_t size = count;
if (ret != size)
iov_iter_revert(from, size-ret);
[1] WARNING: lib/iov_iter.c:1090
Call Trace:
do_tty_write drivers/tty/tty_io.c:967 [inline]
file_tty_write.constprop.0+0x55f/0x8f0 drivers/tty/tty_io.c:1048
call_write_iter include/linux/fs.h:1901 [inline]
new_sync_write+0x426/0x650 fs/read_write.c:518
vfs_write+0x791/0xa30 fs/read_write.c:605
ksys_write+0x12d/0x250 fs/read_write.c:658
Fixes: 494e63ee9c("tty: implement write_iter")
Reported-by: syzbot+3d2c27c2b7dc2a94814d@syzkaller.appspotmail.com
Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@gmail.com>
---
drivers/tty/tty_io.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 816e709afa56..8d6d579ecc3b 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -905,6 +905,9 @@ static inline ssize_t do_tty_write(
ssize_t ret, written = 0;
unsigned int chunk;
+ if (!count)
+ return -EINVAL;
+
ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
if (ret < 0)
return ret;
--
2.25.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] tty: fix when iov_iter_count() returns 0 in tty_write()
2021-02-17 14:43 [PATCH] tty: fix when iov_iter_count() returns 0 in tty_write() Sabyrzhan Tasbolatov
@ 2021-02-17 15:13 ` Greg KH
2021-02-17 15:15 ` Greg KH
0 siblings, 1 reply; 5+ messages in thread
From: Greg KH @ 2021-02-17 15:13 UTC (permalink / raw)
To: Sabyrzhan Tasbolatov; +Cc: jirislaby, linux-kernel, syzbot+3d2c27c2b7dc2a94814d
On Wed, Feb 17, 2021 at 08:43:47PM +0600, Sabyrzhan Tasbolatov wrote:
> syzbot found WARNING in iov_iter_revert[1] when iov_iter_count() returns 0,
> therefore INT_MAX is passed to iov_iter_revert() causing > MAX_RW_COUNT
> warning.
>
> static inline ssize_t do_tty_write()
> {
> ..
> size_t count = iov_iter_count(from);
> ..
> size_t size = count;
> if (ret != size)
> iov_iter_revert(from, size-ret);
>
> [1] WARNING: lib/iov_iter.c:1090
> Call Trace:
> do_tty_write drivers/tty/tty_io.c:967 [inline]
> file_tty_write.constprop.0+0x55f/0x8f0 drivers/tty/tty_io.c:1048
> call_write_iter include/linux/fs.h:1901 [inline]
> new_sync_write+0x426/0x650 fs/read_write.c:518
> vfs_write+0x791/0xa30 fs/read_write.c:605
> ksys_write+0x12d/0x250 fs/read_write.c:658
>
> Fixes: 494e63ee9c("tty: implement write_iter")
Nit, you need a ' ' before your '(' character here, otherwise the
linux-next scripts will complain.
> Reported-by: syzbot+3d2c27c2b7dc2a94814d@syzkaller.appspotmail.com
> Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@gmail.com>
> ---
> drivers/tty/tty_io.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
> index 816e709afa56..8d6d579ecc3b 100644
> --- a/drivers/tty/tty_io.c
> +++ b/drivers/tty/tty_io.c
> @@ -905,6 +905,9 @@ static inline ssize_t do_tty_write(
> ssize_t ret, written = 0;
> unsigned int chunk;
>
> + if (!count)
> + return -EINVAL;
According to the man page for write(2), I think this is the wrong error
value to return, unless that is the value that was returned on kernels
before the commit listed above.
Can you verify this?
thanks,
greg k-h
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] tty: fix when iov_iter_count() returns 0 in tty_write()
2021-02-17 15:13 ` Greg KH
@ 2021-02-17 15:15 ` Greg KH
2021-02-17 15:55 ` [PATCH v2] " Sabyrzhan Tasbolatov
0 siblings, 1 reply; 5+ messages in thread
From: Greg KH @ 2021-02-17 15:15 UTC (permalink / raw)
To: Sabyrzhan Tasbolatov; +Cc: jirislaby, linux-kernel, syzbot+3d2c27c2b7dc2a94814d
On Wed, Feb 17, 2021 at 04:13:58PM +0100, Greg KH wrote:
> On Wed, Feb 17, 2021 at 08:43:47PM +0600, Sabyrzhan Tasbolatov wrote:
> > syzbot found WARNING in iov_iter_revert[1] when iov_iter_count() returns 0,
> > therefore INT_MAX is passed to iov_iter_revert() causing > MAX_RW_COUNT
> > warning.
> >
> > static inline ssize_t do_tty_write()
> > {
> > ..
> > size_t count = iov_iter_count(from);
> > ..
> > size_t size = count;
> > if (ret != size)
> > iov_iter_revert(from, size-ret);
> >
> > [1] WARNING: lib/iov_iter.c:1090
> > Call Trace:
> > do_tty_write drivers/tty/tty_io.c:967 [inline]
> > file_tty_write.constprop.0+0x55f/0x8f0 drivers/tty/tty_io.c:1048
> > call_write_iter include/linux/fs.h:1901 [inline]
> > new_sync_write+0x426/0x650 fs/read_write.c:518
> > vfs_write+0x791/0xa30 fs/read_write.c:605
> > ksys_write+0x12d/0x250 fs/read_write.c:658
> >
> > Fixes: 494e63ee9c("tty: implement write_iter")
>
> Nit, you need a ' ' before your '(' character here, otherwise the
> linux-next scripts will complain.
Also, you got the git commit id wrong, so this needs to be fixed up
anyway. You are pointing to a merge point, I doubt that's what you want
to point to here, right?
thanks,
greg k-h
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH v2] tty: fix when iov_iter_count() returns 0 in tty_write()
2021-02-17 15:15 ` Greg KH
@ 2021-02-17 15:55 ` Sabyrzhan Tasbolatov
2021-02-19 9:17 ` Jiri Slaby
0 siblings, 1 reply; 5+ messages in thread
From: Sabyrzhan Tasbolatov @ 2021-02-17 15:55 UTC (permalink / raw)
To: gregkh; +Cc: jirislaby, linux-kernel, snovitoll, syzbot+3d2c27c2b7dc2a94814d
syzbot found WARNING in iov_iter_revert[1] when iov_iter_count() returns 0,
therefore INT_MAX is passed to iov_iter_revert() causing > MAX_RW_COUNT
warning.
static inline ssize_t do_tty_write()
{
..
size_t count = iov_iter_count(from);
..
size_t size = count;
if (ret != size)
iov_iter_revert(from, size-ret);
[1] WARNING: lib/iov_iter.c:1090
Call Trace:
do_tty_write drivers/tty/tty_io.c:967 [inline]
file_tty_write.constprop.0+0x55f/0x8f0 drivers/tty/tty_io.c:1048
call_write_iter include/linux/fs.h:1901 [inline]
new_sync_write+0x426/0x650 fs/read_write.c:518
vfs_write+0x791/0xa30 fs/read_write.c:605
ksys_write+0x12d/0x250 fs/read_write.c:658
Fixes: 9bb48c82aced ("tty: implement write_iter")
Reported-by: syzbot+3d2c27c2b7dc2a94814d@syzkaller.appspotmail.com
Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@gmail.com>
---
v2: Fixed "Fixed" tag to proper commit and changed write return to -EFAULT
as this statement is valid, tested via strace:
write(3, NULL, 0) = -1 EFAULT (Bad address)
Updated to -EFAULT, should be a valid exit code as
copy_from_iter(.., .., from) returns -EFAULT as well if *from is invalid
address.
>
> Nit, you need a ' ' before your '(' character here, otherwise the
> linux-next scripts will complain.
> Also, you got the git commit id wrong, so this needs to be fixed up
> anyway. You are pointing to a merge point, I doubt that's what you want
> to point to here, right?
Thanks!
---
drivers/tty/tty_io.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 816e709afa56..e1460cad8b7d 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -905,6 +905,9 @@ static inline ssize_t do_tty_write(
ssize_t ret, written = 0;
unsigned int chunk;
+ if (!count)
+ return -EFAULT;
+
ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
if (ret < 0)
return ret;
--
2.25.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH v2] tty: fix when iov_iter_count() returns 0 in tty_write()
2021-02-17 15:55 ` [PATCH v2] " Sabyrzhan Tasbolatov
@ 2021-02-19 9:17 ` Jiri Slaby
0 siblings, 0 replies; 5+ messages in thread
From: Jiri Slaby @ 2021-02-19 9:17 UTC (permalink / raw)
To: Sabyrzhan Tasbolatov, gregkh; +Cc: linux-kernel, syzbot+3d2c27c2b7dc2a94814d
On 17. 02. 21, 16:55, Sabyrzhan Tasbolatov wrote:
> syzbot found WARNING in iov_iter_revert[1] when iov_iter_count() returns 0,
> therefore INT_MAX is passed to iov_iter_revert() causing > MAX_RW_COUNT
> warning.
>
> static inline ssize_t do_tty_write()
> {
> ..
> size_t count = iov_iter_count(from);
> ..
> size_t size = count;
> if (ret != size)
> iov_iter_revert(from, size-ret);
>
> [1] WARNING: lib/iov_iter.c:1090
> Call Trace:
> do_tty_write drivers/tty/tty_io.c:967 [inline]
> file_tty_write.constprop.0+0x55f/0x8f0 drivers/tty/tty_io.c:1048
> call_write_iter include/linux/fs.h:1901 [inline]
> new_sync_write+0x426/0x650 fs/read_write.c:518
> vfs_write+0x791/0xa30 fs/read_write.c:605
> ksys_write+0x12d/0x250 fs/read_write.c:658
>
> Fixes: 9bb48c82aced ("tty: implement write_iter")
> Reported-by: syzbot+3d2c27c2b7dc2a94814d@syzkaller.appspotmail.com
> Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@gmail.com>
> ---
>
> v2: Fixed "Fixed" tag to proper commit and changed write return to -EFAULT
> as this statement is valid, tested via strace:
>
> write(3, NULL, 0) = -1 EFAULT (Bad address)
>
> Updated to -EFAULT, should be a valid exit code as
> copy_from_iter(.., .., from) returns -EFAULT as well if *from is invalid
> address.
Exactly, EFAULT is for invalid memory accesses. But this should be IMO
EINVAL as it's an invalid argument.
BTW what's the reason vfs calls ->write with zero count of iter?
>> Nit, you need a ' ' before your '(' character here, otherwise the
>> linux-next scripts will complain.
>
>> Also, you got the git commit id wrong, so this needs to be fixed up
>> anyway. You are pointing to a merge point, I doubt that's what you want
>> to point to here, right?
>
> Thanks!
> ---
> drivers/tty/tty_io.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
> index 816e709afa56..e1460cad8b7d 100644
> --- a/drivers/tty/tty_io.c
> +++ b/drivers/tty/tty_io.c
> @@ -905,6 +905,9 @@ static inline ssize_t do_tty_write(
> ssize_t ret, written = 0;
> unsigned int chunk;
>
> + if (!count)
> + return -EFAULT;
> +
> ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
> if (ret < 0)
> return ret;
>
--
js
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-02-19 9:18 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2021-02-17 14:43 [PATCH] tty: fix when iov_iter_count() returns 0 in tty_write() Sabyrzhan Tasbolatov
2021-02-17 15:13 ` Greg KH
2021-02-17 15:15 ` Greg KH
2021-02-17 15:55 ` [PATCH v2] " Sabyrzhan Tasbolatov
2021-02-19 9:17 ` Jiri Slaby
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