diff options
| author | Joe Lawrence <joe.lawrence@redhat.com> | 2017-11-17 15:29:24 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-11-17 16:10:03 -0800 |
| commit | 7a8d181949fb2c16be00f8cdb354794a30e46b39 (patch) | |
| tree | 4f18ea1b17605e97a2c5a0089ff819eb60435bc9 /include | |
| parent | d3f14c485867cfb2e0c48aa88c41d0ef4bf5209c (diff) | |
| download | linux-7a8d181949fb2c16be00f8cdb354794a30e46b39.tar.gz | |
pipe: add proc_dopipe_max_size() to safely assign pipe_max_size
pipe_max_size is assigned directly via procfs sysctl:
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,
},
...
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)
...
and then later rounded in-place a few statements later:
...
pipe_max_size = round_pipe_size(pipe_max_size);
...
This leaves a window of time between initial assignment and rounding
that may be visible to other threads. (For example, one thread sets a
non-rounded value to pipe_max_size while another reads its value.)
Similar reads of pipe_max_size are potentially racy:
pipe.c :: alloc_pipe_info()
pipe.c :: pipe_set_size()
Add a new proc_dopipe_max_size() that consolidates reading the new value
from the user buffer, verifying bounds, and calling round_pipe_size()
with a single assignment to pipe_max_size.
Link: http://lkml.kernel.org/r/1507658689-11669-4-git-send-email-joe.lawrence@redhat.com
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Reported-by: Mikulas Patocka <mpatocka@redhat.com>
Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/pipe_fs_i.h | 1 | ||||
| -rw-r--r-- | include/linux/sysctl.h | 3 |
2 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h index 6a80cfc63e0c..2dc5e9870fcd 100644 --- a/include/linux/pipe_fs_i.h +++ b/include/linux/pipe_fs_i.h @@ -191,5 +191,6 @@ long pipe_fcntl(struct file *, unsigned int, unsigned long arg); struct pipe_inode_info *get_pipe_info(struct file *file); int create_pipe_files(struct file **, int); +unsigned int round_pipe_size(unsigned int size); #endif diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h index b769ecfcc3bd..992bc9948232 100644 --- a/include/linux/sysctl.h +++ b/include/linux/sysctl.h @@ -51,6 +51,9 @@ extern int proc_dointvec_minmax(struct ctl_table *, int, extern int proc_douintvec_minmax(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos); +extern int proc_dopipe_max_size(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos); extern int proc_dointvec_jiffies(struct ctl_table *, int, void __user *, size_t *, loff_t *); extern int proc_dointvec_userhz_jiffies(struct ctl_table *, int, |