tracing: Have the histogram compare functions convert to u64 first
authorSteven Rostedt (VMware) <rostedt@goodmis.org>
Wed, 11 Dec 2019 20:44:22 +0000 (15:44 -0500)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 9 Jan 2020 09:19:02 +0000 (10:19 +0100)
commit0c815959304bee255034c8ba9f3668a1ae380f86
treed5cf53d28ad5ca68abf4b486cf0f5acd4c417342
parent8595e2aaddd8c35db02aa2f35eab8e04d8b0f39d
tracing: Have the histogram compare functions convert to u64 first

commit 106f41f5a302cb1f36c7543fae6a05de12e96fa4 upstream.

The compare functions of the histogram code would be specific for the size
of the value being compared (byte, short, int, long long). It would
reference the value from the array via the type of the compare, but the
value was stored in a 64 bit number. This is fine for little endian
machines, but for big endian machines, it would end up comparing zeros or
all ones (depending on the sign) for anything but 64 bit numbers.

To fix this, first derference the value as a u64 then convert it to the type
being compared.

Link: http://lkml.kernel.org/r/20191211103557.7bed6928@gandalf.local.home
Cc: stable@vger.kernel.org
Fixes: 08d43a5fa063e ("tracing: Add lock-free tracing_map")
Acked-by: Tom Zanussi <zanussi@kernel.org>
Reported-by: Sven Schnelle <svens@stackframe.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kernel/trace/tracing_map.c