3.16.57-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Eric Biggers <ebiggers@xxxxxxxxxx> commit 4c2e4befb3cc9ce42d506aa537c9ab504723e98c upstream. Patch series "pipe: buffer limits fixes and cleanups", v2. This series simplifies the sysctl handler for pipe-max-size and fixes another set of bugs related to the pipe buffer limits: - The root user wasn't allowed to exceed the limits when creating new pipes. - There was an off-by-one error when checking the limits, so a limit of N was actually treated as N - 1. - F_SETPIPE_SZ accepted values over UINT_MAX. - Reading the pipe buffer limits could be racy. This patch (of 7): Before validating the given value against pipe_min_size, do_proc_dopipe_max_size_conv() calls round_pipe_size(), which rounds the value up to pipe_min_size. Therefore, the second check against pipe_min_size is redundant. Remove it. Link: http://lkml.kernel.org/r/20180111052902.14409-2-ebiggers3@xxxxxxxxx Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx> Acked-by: Kees Cook <keescook@xxxxxxxxxxxx> Acked-by: Joe Lawrence <joe.lawrence@xxxxxxxxxx> Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: "Luis R . Rodriguez" <mcgrof@xxxxxxxxxx> Cc: Michael Kerrisk <mtk.manpages@xxxxxxxxx> Cc: Mikulas Patocka <mpatocka@xxxxxxxxxx> Cc: Willy Tarreau <w@xxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> --- fs/pipe.c | 10 +++------- include/linux/pipe_fs_i.h | 2 +- kernel/sysctl.c | 15 +-------------- 3 files changed, 5 insertions(+), 22 deletions(-) --- a/fs/pipe.c +++ b/fs/pipe.c @@ -34,11 +34,6 @@ */ unsigned int pipe_max_size = 1048576; -/* - * Minimum pipe size, as required by POSIX - */ -unsigned int pipe_min_size = PAGE_SIZE; - /* Maximum allocatable pages per user. Hard limit is unset by default, soft * matches default values. */ @@ -1012,8 +1007,9 @@ unsigned int round_pipe_size(unsigned in { unsigned long nr_pages; - if (size < pipe_min_size) - size = pipe_min_size; + /* Minimum pipe size, as required by POSIX */ + if (size < PAGE_SIZE) + size = PAGE_SIZE; nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; if (nr_pages == 0) --- a/include/linux/pipe_fs_i.h +++ b/include/linux/pipe_fs_i.h @@ -124,7 +124,7 @@ void pipe_lock(struct pipe_inode_info *) void pipe_unlock(struct pipe_inode_info *); void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *); -extern unsigned int pipe_max_size, pipe_min_size; +extern unsigned int pipe_max_size; extern unsigned long pipe_user_pages_hard; extern unsigned long pipe_user_pages_soft; int pipe_proc_fn(struct ctl_table *, int, void __user *, size_t *, loff_t *); --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -1672,7 +1672,6 @@ static struct ctl_table fs_table[] = { .maxlen = sizeof(int), .mode = 0644, .proc_handler = &pipe_proc_fn, - .extra1 = &pipe_min_size, }, { .procname = "pipe-user-pages-hard", @@ -2223,15 +2222,9 @@ int proc_dointvec_minmax(struct ctl_tabl do_proc_dointvec_minmax_conv, ¶m); } -struct do_proc_dopipe_max_size_conv_param { - unsigned int *min; -}; - static int do_proc_dopipe_max_size_conv(bool *negp, unsigned long *lvalp, int *valp, int write, void *data) { - struct do_proc_dopipe_max_size_conv_param *param = data; - if (write) { unsigned int val; @@ -2242,9 +2235,6 @@ static int do_proc_dopipe_max_size_conv( if (*negp || val == 0) return -EINVAL; - if (param->min && *param->min > val) - return -ERANGE; - *valp = val; } else { unsigned int val = *valp; @@ -2258,11 +2248,8 @@ static int do_proc_dopipe_max_size_conv( int proc_dopipe_max_size(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) { - struct do_proc_dopipe_max_size_conv_param param = { - .min = (unsigned int *) table->extra1, - }; return do_proc_dointvec(table, write, buffer, lenp, ppos, - do_proc_dopipe_max_size_conv, ¶m); + do_proc_dopipe_max_size_conv, NULL); } static void validate_coredump_safety(void)
