From 2f7c68cb55ecb7331f2381deb497c27155f32faf Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Wed, 03 Jan 2024 09:43:39 +0000
Subject: [PATCH] update kernel to 5.10.198
---
kernel/fs/file.c | 25 ++++++++++++++++++++-----
1 files changed, 20 insertions(+), 5 deletions(-)
diff --git a/kernel/fs/file.c b/kernel/fs/file.c
index 97a0cd3..d6bc739 100644
--- a/kernel/fs/file.c
+++ b/kernel/fs/file.c
@@ -677,6 +677,7 @@
fdt = files_fdtable(files);
if (fd >= fdt->max_fds)
goto out_unlock;
+ fd = array_index_nospec(fd, fdt->max_fds);
file = fdt->fd[fd];
if (!file)
goto out_unlock;
@@ -1006,16 +1007,30 @@
return __fget_light(fd, 0);
}
+/*
+ * Try to avoid f_pos locking. We only need it if the
+ * file is marked for FMODE_ATOMIC_POS, and it can be
+ * accessed multiple ways.
+ *
+ * Always do it for directories, because pidfd_getfd()
+ * can make a file accessible even if it otherwise would
+ * not be, and for directories this is a correctness
+ * issue, not a "POSIX requirement".
+ */
+static inline bool file_needs_f_pos_lock(struct file *file)
+{
+ return (file->f_mode & FMODE_ATOMIC_POS) &&
+ (file_count(file) > 1 || S_ISDIR(file_inode(file)->i_mode));
+}
+
unsigned long __fdget_pos(unsigned int fd)
{
unsigned long v = __fdget(fd);
struct file *file = (struct file *)(v & ~3);
- if (file && (file->f_mode & FMODE_ATOMIC_POS)) {
- if (file_count(file) > 1) {
- v |= FDPUT_POS_UNLOCK;
- mutex_lock(&file->f_pos_lock);
- }
+ if (file && file_needs_f_pos_lock(file)) {
+ v |= FDPUT_POS_UNLOCK;
+ mutex_lock(&file->f_pos_lock);
}
return v;
}
--
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