| Message ID | 20200817220425.9389-15-ebiederm@xmission.com |
|---|---|
| State | Not Applicable |
| Delegated to: | David Miller |
| Headers | show |
| Series | [01/17] exec: Move unshare_files to fix posix file locking during exec | expand |
On Mon, Aug 17, 2020 at 05:04:23PM -0500, Eric W. Biederman wrote: > Simplify the code, and remove the chance of races by reading > RLIMIT_NOFILE only once in f_dupfd. > > Pass the read value of RLIMIT_NOFILE into alloc_fd which is the other > location the rlimit was read in f_dupfd. As f_dupfd is the only > caller of alloc_fd this changing alloc_fd is trivially safe. > > Further this causes alloc_fd to take all of the same arguments as > __alloc_fd except for the files_struct argument. > > Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> > --- Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
diff --git a/fs/file.c b/fs/file.c index 1a755811669d..505b2e81ad3e 100644 --- a/fs/file.c +++ b/fs/file.c @@ -523,9 +523,9 @@ int __alloc_fd(struct files_struct *files, return error; } -static int alloc_fd(unsigned start, unsigned flags) +static int alloc_fd(unsigned start, unsigned end, unsigned flags) { - return __alloc_fd(current->files, start, rlimit(RLIMIT_NOFILE), flags); + return __alloc_fd(current->files, start, end, flags); } int __get_unused_fd_flags(unsigned flags, unsigned long nofile) @@ -1158,10 +1158,11 @@ SYSCALL_DEFINE1(dup, unsigned int, fildes) int f_dupfd(unsigned int from, struct file *file, unsigned flags) { + unsigned long nofile = rlimit(RLIMIT_NOFILE); int err; - if (from >= rlimit(RLIMIT_NOFILE)) + if (from >= nofile) return -EINVAL; - err = alloc_fd(from, flags); + err = alloc_fd(from, nofile, flags); if (err >= 0) { get_file(file); fd_install(err, file);
Simplify the code, and remove the chance of races by reading RLIMIT_NOFILE only once in f_dupfd. Pass the read value of RLIMIT_NOFILE into alloc_fd which is the other location the rlimit was read in f_dupfd. As f_dupfd is the only caller of alloc_fd this changing alloc_fd is trivially safe. Further this causes alloc_fd to take all of the same arguments as __alloc_fd except for the files_struct argument. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> --- fs/file.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)