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| author | Eric W. Biederman <ebiederm@xmission.com> | 2020-11-20 17:14:36 -0600 |
|---|---|---|
| committer | Eric W. Biederman <ebiederm@xmission.com> | 2020-12-10 12:42:59 -0600 |
| commit | e06b53c22f31ebba4c46d02fb3a58336135db45c (patch) | |
| tree | 133bb1ff44d98374290fc7e145f213598fd27811 /fs/file.c | |
| parent | d74ba04d919ebe30bf47406819c18c6b50003d92 (diff) | |
| download | lwn-e06b53c22f31ebba4c46d02fb3a58336135db45c.tar.gz lwn-e06b53c22f31ebba4c46d02fb3a58336135db45c.zip | |
file: In f_dupfd read RLIMIT_NOFILE once.
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.
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
v1: https://lkml.kernel.org/r/20200817220425.9389-15-ebiederm@xmission.com
Link: https://lkml.kernel.org/r/20201120231441.29911-19-ebiederm@xmission.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Diffstat (limited to 'fs/file.c')
| -rw-r--r-- | fs/file.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/fs/file.c b/fs/file.c index 0d4ec0fa23b3..07e25f1b9dfd 100644 --- a/fs/file.c +++ b/fs/file.c @@ -538,9 +538,9 @@ out: 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) @@ -1175,10 +1175,11 @@ 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); |