From: David Laight <David.Laight@ACULAB.COM>
To: 'Matthew Wilcox' <willy@infradead.org>
Cc: 'Kent Overstreet' <kent.overstreet@gmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@vger.kernel.org" <linux-mm@vger.kernel.org>,
"pmladek@suse.com" <pmladek@suse.com>,
"rostedt@goodmis.org" <rostedt@goodmis.org>,
"senozhatsky@chromium.org" <senozhatsky@chromium.org>,
"andriy.shevchenko@linux.intel.com"
<andriy.shevchenko@linux.intel.com>
Subject: RE: [PATCH v2 03/28] vsprintf: %pf(%p)
Date: Fri, 20 May 2022 08:03:29 +0000 [thread overview]
Message-ID: <786516a0b71a4c6689592b89b146edec@AcuMS.aculab.com> (raw)
In-Reply-To: <Yoazbys+LiG0Uqcc@casper.infradead.org>
From: Matthew Wilcox
> Sent: 19 May 2022 22:15
>
> On Thu, May 19, 2022 at 09:06:24PM +0000, David Laight wrote:
> > I suspect this a very good way to blow the kernel stack.
> > The highest stack use is already very likely to be inside
> > the printf code in an error path somewhere.
>
> ...
>
> > Double copying using a temporary buffer isn't the end of the world.
>
> How can you hold both of these positions simultaneously?
Mostly you only need a short(ish) buffer to format a single item.
But even a full line buffer is probably less stack than a
nested printf call.
It certainly makes it possible for static analysis to determine
maximum stack depth.
That made me realise that one of the problems doing static
analysis of stack depth is indirect calls.
The hashes that (IIRC) fine-ibt add to indirect calls
and functions make it possible to tie these together.
So you can determine the worst one of the called functions
and use it for the stack depth at the call sites.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2022-05-20 8:03 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-19 17:23 [PATCH v2 00/28] Printbufs (now with more printbufs!) Kent Overstreet
2022-05-19 17:23 ` [PATCH v2 01/28] lib/printbuf: New data structure for printing strings Kent Overstreet
2022-05-19 18:21 ` Matthew Wilcox
2022-05-20 4:44 ` Kent Overstreet
2022-05-26 15:06 ` Petr Mladek
2022-05-26 15:21 ` Kent Overstreet
2022-05-26 15:36 ` Joe Perches
2022-05-27 10:29 ` Petr Mladek
2022-05-29 18:15 ` Kent Overstreet
2022-05-31 22:03 ` Kent Overstreet
2022-05-19 17:23 ` [PATCH v2 02/28] vsprintf: Convert to printbuf Kent Overstreet
2022-05-19 17:23 ` [PATCH v2 03/28] vsprintf: %pf(%p) Kent Overstreet
2022-05-19 18:33 ` Matthew Wilcox
2022-05-20 4:43 ` Kent Overstreet
2022-05-19 21:06 ` David Laight
2022-05-19 21:15 ` Matthew Wilcox
2022-05-20 8:03 ` David Laight [this message]
2022-05-20 13:08 ` Matthew Wilcox
2022-05-20 4:49 ` Kent Overstreet
2022-05-20 14:17 ` andriy.shevchenko
2022-05-19 21:20 ` Matthew Wilcox
2022-05-20 7:40 ` Michal Hocko
2022-05-20 15:01 ` Kent Overstreet
2022-05-20 17:56 ` Kent Overstreet
2022-05-19 17:23 ` [PATCH v2 04/28] lib/string_helpers: string_get_size() now returns characters wrote Kent Overstreet
2022-05-19 17:23 ` [PATCH v2 05/28] lib/printbuf: Heap allocation Kent Overstreet
2022-05-19 17:23 ` [PATCH v2 06/28] lib/printbuf: Tabstops, indenting Kent Overstreet
2022-05-19 17:24 ` [PATCH v2 07/28] lib/printbuf: Unit specifiers Kent Overstreet
2022-05-19 20:21 ` Andy Shevchenko
2022-05-19 20:26 ` Kent Overstreet
2022-05-19 21:11 ` Matthew Wilcox
2022-05-20 4:40 ` Kent Overstreet
2022-05-19 21:16 ` Andy Shevchenko
2022-05-19 21:22 ` Matthew Wilcox
2022-05-20 4:36 ` Kent Overstreet
2022-05-19 17:24 ` [PATCH v2 08/28] lib/pretty-printers: pr_string_option(), pr_bitflags() Kent Overstreet
2022-05-19 17:24 ` [PATCH v2 09/28] vsprintf: Improve number() Kent Overstreet
2022-05-19 17:24 ` [PATCH v2 10/28] vsprintf: pr_u64_minwidth(), pr_u64() Kent Overstreet
2022-05-19 17:24 ` [PATCH v2 11/28] vsprintf: Lift pr_hex_bytes() out from hex_string() Kent Overstreet
2022-05-19 17:24 ` [PATCH v2 12/28] test_printf: Drop requirement that sprintf not write past nul Kent Overstreet
2022-05-19 17:24 ` [PATCH v2 13/28] vsprintf: Start consolidating printf_spec handling Kent Overstreet
2022-05-19 17:24 ` [PATCH v2 14/28] vsprintf: Refactor resource_string() Kent Overstreet
2022-05-19 17:24 ` [PATCH v2 15/28] vsprintf: Refactor fourcc_string() Kent Overstreet
2022-05-19 17:24 ` [PATCH v2 16/28] vsprintf: Refactor ip_addr_string() Kent Overstreet
2022-05-19 17:24 ` [PATCH v2 17/28] vsprintf: Refactor mac_address_string() Kent Overstreet
2022-05-19 17:24 ` [PATCH v2 18/28] vsprintf: time_and_date() no longer takes printf_spec Kent Overstreet
2022-05-19 17:24 ` [PATCH v2 19/28] vsprintf: flags_string() " Kent Overstreet
2022-05-19 17:24 ` [PATCH v2 20/28] vsprintf: Refactor device_node_string, fwnode_string Kent Overstreet
2022-05-19 17:24 ` [PATCH v2 21/28] vsprintf: Refactor hex_string, bitmap_string_list, bitmap_string Kent Overstreet
2022-05-19 17:24 ` [PATCH v2 22/28] Input/joystick/analog: Convert from seq_buf -> printbuf Kent Overstreet
2022-05-19 20:04 ` Andy Shevchenko
2022-05-19 20:19 ` Kent Overstreet
2022-05-19 21:09 ` Andy Shevchenko
2022-05-19 17:24 ` [PATCH v2 23/28] mm/memcontrol.c: Convert to printbuf Kent Overstreet
2022-05-20 7:59 ` Michal Hocko
2022-05-19 17:24 ` [PATCH v2 24/28] clk: tegra: bpmp: " Kent Overstreet
2022-05-19 17:24 ` [PATCH v2 25/28] tools/testing/nvdimm: " Kent Overstreet
2022-05-19 17:24 ` [PATCH v2 26/28] powerpc: " Kent Overstreet
2022-05-19 17:24 ` [PATCH v2 27/28] x86/resctrl: " Kent Overstreet
2022-05-19 17:24 ` [PATCH v2 28/28] PCI/P2PDMA: " Kent Overstreet
2022-05-26 14:44 ` [PATCH v2 00/28] Printbufs (now with more printbufs!) Petr Mladek
2022-05-26 15:11 ` Kent Overstreet
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