| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <65069ee9b3b92d92773fa556c45507158eb9c84f.camel@foss.st.com>
Date: Fri, 1 Jul 2022 11:15:38 +0200
From: Antonio Borneo <antonio.borneo@...s.st.com>
To: Petr Mladek <pmladek@...e.com>
CC: Jan Kiszka <jan.kiszka@...mens.com>,
Kieran Bingham <kbingham@...nel.org>,
John Ogness <john.ogness@...utronix.de>,
<linux-kernel@...r.kernel.org>,
<linux-stm32@...md-mailman.stormreply.com>
Subject: Re: [PATCH] scripts/gdb: fix 'lx-dmesg' on 32 bits arch
On Thu, 2022-06-30 at 15:13 +0200, Petr Mladek wrote:
> On Fri 2022-06-17 16:37:58, Antonio Borneo wrote:
> > The type atomic_long_t can have size 4 or 8 bytes, depending on
> > CONFIG_64BIT; it's only content, the field 'counter', is either an
> > int or a s64 value.
> >
> > Current code incorrectly uses the fixed size utils.read_u64() to
> > read the field 'counter' inside atomic_long_t.
> >
> > On 32 bits architectures reading the last element 'tail_id' of the
> > struct prb_desc_ring:
> > struct prb_desc_ring {
> > ...
> > atomic_long_t tail_id;
> > };
> > causes the utils.read_u64() to access outside the boundary of the
> > struct and the gdb command 'lx-dmesg' exits with error:
> > Python Exception <class 'IndexError'>: index out of range
> > Error occurred in Python: index out of range
> >
> > Use the existing utils.read_ulong() to read 'counter' inside the
> > atomic_long_t.
>
> I was about to accept this. But then I wondered if we could somehow
> detect the really used atomic_long_t counter type size.
>
> I have updated your patch. It works for me on x86_64.
> Could you please check it on 32-bit system?
Tested on 32 bits Cortex-A7 STM32MP157, it works fine.
Yes, agree on your rework; definitively cleaner.
Thanks,
Antonio
> Here is the patch:
>
> From bb5b6a7ad6f4339a1102585c691cb725182c0acf Mon Sep 17 00:00:00
> 2001
> From: Antonio Borneo <antonio.borneo@...s.st.com>
> Date: Fri, 17 Jun 2022 16:37:58 +0200
> Subject: [PATCH] scripts/gdb: fix 'lx-dmesg' on 32 bits arch
>
> The type atomic_long_t can have size 4 or 8 bytes, depending on
> CONFIG_64BIT; it's only content, the field 'counter', is either an
> int or a s64 value.
>
> Current code incorrectly uses the fixed size utils.read_u64() to
> read the field 'counter' inside atomic_long_t.
>
> On 32 bits architectures reading the last element 'tail_id' of the
> struct prb_desc_ring:
> struct prb_desc_ring {
> ...
> atomic_long_t tail_id;
> };
> causes the utils.read_u64() to access outside the boundary of the
> struct and the gdb command 'lx-dmesg' exits with error:
> Python Exception <class 'IndexError'>: index out of range
> Error occurred in Python: index out of range
>
> Query the really used atomic_long_t counter type size.
>
> Fixes: e60768311af8 ("scripts/gdb: update for lockless printk
> ringbuffer")
> Signed-off-by: Antonio Borneo <antonio.borneo@...s.st.com>
> [pmladek@...e.com: Query the really used atomic_long_t counter type
> size]
> Link:
> https://lore.kernel.org/r/20220617143758.137307-1-antonio.borneo@foss.st.com
> ---
> scripts/gdb/linux/dmesg.py | 9 +++------
> scripts/gdb/linux/utils.py | 14 ++++++++++++--
> 2 files changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/scripts/gdb/linux/dmesg.py b/scripts/gdb/linux/dmesg.py
> index d5983cf3db7d..c771831eb077 100644
> --- a/scripts/gdb/linux/dmesg.py
> +++ b/scripts/gdb/linux/dmesg.py
> @@ -22,7 +22,6 @@ prb_desc_type = utils.CachedType("struct prb_desc")
> prb_desc_ring_type = utils.CachedType("struct prb_desc_ring")
> prb_data_ring_type = utils.CachedType("struct prb_data_ring")
> printk_ringbuffer_type = utils.CachedType("struct
> printk_ringbuffer")
> -atomic_long_type = utils.CachedType("atomic_long_t")
>
> class LxDmesg(gdb.Command):
> """Print Linux kernel log buffer."""
> @@ -68,8 +67,6 @@ class LxDmesg(gdb.Command):
> off = prb_data_ring_type.get_type()['data'].bitpos // 8
> text_data_addr = utils.read_ulong(text_data_ring, off)
>
> - counter_off = atomic_long_type.get_type()['counter'].bitpos
> // 8
> -
> sv_off = prb_desc_type.get_type()['state_var'].bitpos // 8
>
> off = prb_desc_type.get_type()['text_blk_lpos'].bitpos // 8
> @@ -89,9 +86,9 @@ class LxDmesg(gdb.Command):
>
> # read in tail and head descriptor ids
> off = prb_desc_ring_type.get_type()['tail_id'].bitpos // 8
> - tail_id = utils.read_u64(desc_ring, off + counter_off)
> + tail_id = utils.read_atomic_long(desc_ring, off)
> off = prb_desc_ring_type.get_type()['head_id'].bitpos // 8
> - head_id = utils.read_u64(desc_ring, off + counter_off)
> + head_id = utils.read_atomic_long(desc_ring, off)
>
> did = tail_id
> while True:
> @@ -102,7 +99,7 @@ class LxDmesg(gdb.Command):
> desc = utils.read_memoryview(inf, desc_addr + desc_off,
> desc_sz).tobytes()
>
> # skip non-committed record
> - state = 3 & (utils.read_u64(desc, sv_off + counter_off)
> >> desc_flags_shift)
> + state = 3 & (utils.read_atomic_long(desc, sv_off) >>
> desc_flags_shift)
> if state != desc_committed and state != desc_finalized:
> if did == head_id:
> break
> diff --git a/scripts/gdb/linux/utils.py b/scripts/gdb/linux/utils.py
> index ff7c1799d588..1553f68716cc 100644
> --- a/scripts/gdb/linux/utils.py
> +++ b/scripts/gdb/linux/utils.py
> @@ -35,13 +35,12 @@ class CachedType:
>
>
> long_type = CachedType("long")
> -
> +atomic_long_type = CachedType("atomic_long_t")
>
> def get_long_type():
> global long_type
> return long_type.get_type()
>
> -
> def offset_of(typeobj, field):
> element = gdb.Value(0).cast(typeobj)
> return int(str(element[field].address).split()[0], 16)
> @@ -129,6 +128,17 @@ def read_ulong(buffer, offset):
> else:
> return read_u32(buffer, offset)
>
> +atomic_long_counter_offset =
> atomic_long_type.get_type()['counter'].bitpos
> +atomic_long_counter_sizeof =
> atomic_long_type.get_type()['counter'].type.sizeof
> +
> +def read_atomic_long(buffer, offset):
> + global atomic_long_counter_offset
> + global atomic_long_counter_sizeof
> +
> + if atomic_long_counter_sizeof == 8:
> + return read_u64(buffer, offset + atomic_long_counter_offset)
> + else:
> + return read_u32(buffer, offset + atomic_long_counter_offset)
>
> target_arch = None
>
Powered by blists - more mailing lists