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Subject[PATCH RFC 3/3] pipe: match pipe_max_size data type with procfs
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pipe_max_size is defined as an unsigned int:

unsigned int pipe_max_size = 1048576;

but its procfs/sysctl representation is an integer:

static struct ctl_table fs_table[] = {
...
{
.procname = "pipe-max-size",
.data = &pipe_max_size,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &pipe_proc_fn,
.extra1 = &pipe_min_size,
},
...

that is signed:

int pipe_proc_fn(struct ctl_table *table, int write, void __user *buf,
size_t *lenp, loff_t *ppos)
{
...
ret = proc_dointvec_minmax(table, write, buf, lenp, ppos)

This leads to signed results via procfs for large values of
pipe_max_size:

% echo 2147483647 >/proc/sys/fs/pipe-max-size
% cat /proc/sys/fs/pipe-max-size
-2147483648

Use unsigned operations on this variable to avoid such negative values.

Reported-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
---
fs/pipe.c | 2 +-
kernel/sysctl.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/pipe.c b/fs/pipe.c
index 33bb11b0d78e..3b10d39cc5d1 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -1147,7 +1147,7 @@ int pipe_proc_fn(struct ctl_table *table, int write, void __user *buf,

mutex_lock(&pipe_max_mutex);
orig_pipe_max_size = pipe_max_size;
- ret = proc_dointvec_minmax(table, write, buf, lenp, ppos);
+ ret = proc_douintvec_minmax(table, write, buf, lenp, ppos);
if (ret < 0 || !write) {
mutex_unlock(&pipe_max_mutex);
return ret;
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 6648fbbb8157..c976719bf37a 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1825,7 +1825,7 @@ static int sysrq_sysctl_handler(struct ctl_table *table, int write,
{
.procname = "pipe-max-size",
.data = &pipe_max_size,
- .maxlen = sizeof(int),
+ .maxlen = sizeof(pipe_max_size),
.mode = 0644,
.proc_handler = &pipe_proc_fn,
.extra1 = &pipe_min_size,
--
1.8.3.1
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