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tracing: Have the histogram compare functions convert to u64 first

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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: 08d43a5fa0 ("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>
This commit is contained in:
Steven Rostedt (VMware) 2019-12-11 15:44:22 -05:00
parent 79e65c27f0
commit 106f41f5a3
1 changed files with 2 additions and 2 deletions
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4
kernel/trace/tracing_map.c
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@ -148,8 +148,8 @@ static int tracing_map_cmp_atomic64(void *val_a, void *val_b)
#define DEFINE_TRACING_MAP_CMP_FN(type) \
static int tracing_map_cmp_##type(void *val_a, void *val_b) \
{ \
type a = *(type *)val_a; \
type b = *(type *)val_b; \
type a = (type)(*(u64 *)val_a); \
type b = (type)(*(u64 *)val_b); \
\
return (a > b) ? 1 : ((a < b) ? -1 : 0); \
}