5.10-stable review patch. If anyone has any objections, please let me know.
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From: Eric W. Biederman ebiederm@xmission.com
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 Signed-off-by: Chuck Lever chuck.lever@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/file.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/fs/file.c b/fs/file.c index a80deabe7f7dc..9e2b171b92520 100644 --- a/fs/file.c +++ b/fs/file.c @@ -567,9 +567,9 @@ 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) @@ -1235,10 +1235,11 @@ 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);