On Thu, Jun 3, 2010 at 02:13, Arnd Bergmann <arnd@xxxxxxxx> wrote:
> We have shown that the BKL in default_llseek and other
> llseek operations never protects against concurrent access
> from another function:
> --- a/drivers/zorro/proc.c
> +++ b/drivers/zorro/proc.c
> @@ -23,7 +23,7 @@ proc_bus_zorro_lseek(struct file *file, loff_t off, int whence)
> {
> loff_t new = -1;
>
> - lock_kernel();
> + mutex_lock(&file->f_dentry->d_inode->i_mutex);
> switch (whence) {
> case 0:
> new = off;
> @@ -36,10 +36,10 @@ proc_bus_zorro_lseek(struct file *file, loff_t off, int whence)
> break;
> }
> if (new < 0 || new > sizeof(struct ConfigDev)) {
> - unlock_kernel();
> + mutex_unlock(&file->f_dentry->d_inode->i_mutex);
> return -EINVAL;
> }
> - unlock_kernel();
> + mutex_unlock(&file->f_dentry->d_inode->i_mutex);
> return (file->f_pos = new);
> }
I was about to fix this like drivers/pci/proc.c handles it
(origiginally I cloned it from that fil
anyway).
Compared to your version, that also moves the setting of file->f_pos
inside the mutex,
which is probably also needed in other places...
> --- a/drivers/pnp/isapnp/proc.c
> +++ b/drivers/pnp/isapnp/proc.c
> @@ -32,7 +32,7 @@ static loff_t isapnp_proc_bus_lseek(struct file *file, loff_t off, int whence)
> {
> loff_t new = -1;
>
> - lock_kernel();
> + mutex_lock(&file->f_dentry->d_inode->i_mutex);
> switch (whence) {
> case 0:
> new = off;
> @@ -45,10 +45,10 @@ static loff_t isapnp_proc_bus_lseek(struct file *file, loff_t off, int whence)
> break;
> }
> if (new < 0 || new > 256) {
> - unlock_kernel();
> + mutex_unlock(&file->f_dentry->d_inode->i_mutex);
> return -EINVAL;
> }
> - unlock_kernel();
> + mutex_unlock(&file->f_dentry->d_inode->i_mutex);
> return (file->f_pos = new);
... like here?
> }
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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