diff options
Diffstat (limited to 'fs/file.c')
| -rw-r--r-- | fs/file.c | 23 |
1 files changed, 21 insertions, 2 deletions
diff --git a/fs/file.c b/fs/file.c index 5110acb1c9ef..4c6f0ea12c41 100644 --- a/fs/file.c +++ b/fs/file.c @@ -12,6 +12,7 @@ #include <linux/slab.h> #include <linux/vmalloc.h> #include <linux/file.h> +#include <linux/fdtable.h> #include <linux/bitops.h> #include <linux/interrupt.h> #include <linux/spinlock.h> @@ -149,8 +150,16 @@ static struct fdtable * alloc_fdtable(unsigned int nr) nr /= (1024 / sizeof(struct file *)); nr = roundup_pow_of_two(nr + 1); nr *= (1024 / sizeof(struct file *)); - if (nr > sysctl_nr_open) - nr = sysctl_nr_open; + /* + * Note that this can drive nr *below* what we had passed if sysctl_nr_open + * had been set lower between the check in expand_files() and here. Deal + * with that in caller, it's cheaper that way. + * + * We make sure that nr remains a multiple of BITS_PER_LONG - otherwise + * bitmaps handling below becomes unpleasant, to put it mildly... + */ + if (unlikely(nr > sysctl_nr_open)) + nr = ((sysctl_nr_open - 1) | (BITS_PER_LONG - 1)) + 1; fdt = kmalloc(sizeof(struct fdtable), GFP_KERNEL); if (!fdt) @@ -199,6 +208,16 @@ static int expand_fdtable(struct files_struct *files, int nr) if (!new_fdt) return -ENOMEM; /* + * extremely unlikely race - sysctl_nr_open decreased between the check in + * caller and alloc_fdtable(). Cheaper to catch it here... + */ + if (unlikely(new_fdt->max_fds <= nr)) { + free_fdarr(new_fdt); + free_fdset(new_fdt); + kfree(new_fdt); + return -EMFILE; + } + /* * Check again since another task may have expanded the fd table while * we dropped the lock */ |