printk: ringbuffer: Fix truncating buffer size min_t cast
commit 53e9e33e upstream. If an output buffer size exceeded U16_MAX, the min_t(u16, ...) cast in copy_data() was causing writes to truncate. This manifested as output bytes being skipped, seen as %NUL bytes in pstore dumps when the available record size was larger than 65536. Fix the cast to no longer truncate the calculation. Cc: Petr Mladek <pmladek@suse.com> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: John Ogness <john.ogness@linutronix.de> Reported-by:Vijay Balakrishna <vijayb@linux.microsoft.com> Link: https://lore.kernel.org/lkml/d8bb1ec7-a4c5-43a2-9de0-9643a70b899f@linux.microsoft.com/ Fixes: b6cf8b3f ("printk: add lockless ringbuffer") Cc: stable@vger.kernel.org Signed-off-by:
Kees Cook <keescook@chromium.org> Tested-by:
Vijay Balakrishna <vijayb@linux.microsoft.com> Tested-by: Guilherme G. Piccoli <gpiccoli@igalia.com> # Steam Deck Reviewed-by:
Tyler Hicks (Microsoft) <code@tyhicks.com> Tested-by:
Tyler Hicks (Microsoft) <code@tyhicks.com> Reviewed-by:
John Ogness <john.ogness@linutronix.de> Reviewed-by:
Sergey Senozhatsky <senozhatsky@chromium.org> Reviewed-by:
Petr Mladek <pmladek@suse.com> Signed-off-by:
Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20230811054528.never.165-kees@kernel.org Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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8fb1601e
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