From: Tejun Heo <tj@xxxxxxxxxx>
Subject: cpumask: use nr_cpumask_bits for parsing functions
513e3d2d11c9 ("cpumask: always use nr_cpu_ids in formatting and parsing
functions") converted both cpumask printing and parsing functions to use
nr_cpu_ids instead of nr_cpumask_bits. While this was okay for the
printing functions as it just picked one of the two output formats that we
were alternating between depending on a kernel config, doing the same for
parsing wasn't okay.
nr_cpumask_bits can be either nr_cpu_ids or NR_CPUS. We can always use
nr_cpu_ids but that is a variable while NR_CPUS is a constant, so it can
be more efficient to use NR_CPUS when we can get away with it. Converting
the printing functions to nr_cpu_ids makes sense because it affects how
the masks get presented to userspace and doesn't break anything; however,
using nr_cpu_ids for parsing functions can incorrectly leave the higher
bits uninitialized while reading in these masks from userland. As all
testing and comparison functions use nr_cpumask_bits which can be larger
than nr_cpu_ids, the parsed cpumasks can erroneously yield false negative
results.
This made the taskstats interface incorrectly return -EINVAL even when the
inputs were correct.
Fix it by restoring the parse functions to use nr_cpumask_bits instead of
nr_cpu_ids.
Link: http://lkml.kernel.org/r/20170206182442.GB31078@xxxxxxxxxxxxxxx
Fixes: 513e3d2d11c9 ("cpumask: always use nr_cpu_ids in formatting and parsing functions")
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Reported-by: Martin Steigerwald <martin.steigerwald@xxxxxxxxx>
Debugged-by: Ben Hutchings <ben.hutchings@xxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [4.0+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/cpumask.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff -puN include/linux/cpumask.h~cpumask-use-nr_cpumask_bits-for-parsing-functions include/linux/cpumask.h
--- a/include/linux/cpumask.h~cpumask-use-nr_cpumask_bits-for-parsing-functions
+++ a/include/linux/cpumask.h
@@ -560,7 +560,7 @@ static inline void cpumask_copy(struct c
static inline int cpumask_parse_user(const char __user *buf, int len,
struct cpumask *dstp)
{
- return bitmap_parse_user(buf, len, cpumask_bits(dstp), nr_cpu_ids);
+ return bitmap_parse_user(buf, len, cpumask_bits(dstp), nr_cpumask_bits);
}
/**
@@ -575,7 +575,7 @@ static inline int cpumask_parselist_user
struct cpumask *dstp)
{
return bitmap_parselist_user(buf, len, cpumask_bits(dstp),
- nr_cpu_ids);
+ nr_cpumask_bits);
}
/**
@@ -590,7 +590,7 @@ static inline int cpumask_parse(const ch
char *nl = strchr(buf, '\n');
unsigned int len = nl ? (unsigned int)(nl - buf) : strlen(buf);
- return bitmap_parse(buf, len, cpumask_bits(dstp), nr_cpu_ids);
+ return bitmap_parse(buf, len, cpumask_bits(dstp), nr_cpumask_bits);
}
/**
@@ -602,7 +602,7 @@ static inline int cpumask_parse(const ch
*/
static inline int cpulist_parse(const char *buf, struct cpumask *dstp)
{
- return bitmap_parselist(buf, cpumask_bits(dstp), nr_cpu_ids);
+ return bitmap_parselist(buf, cpumask_bits(dstp), nr_cpumask_bits);
}
/**
_
--
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