diff options
| -rw-r--r-- | fs/proc/base.c | 28 |
1 files changed, 23 insertions, 5 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index b6572944efc3..aaffc0c30216 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -235,6 +235,10 @@ static ssize_t get_mm_cmdline(struct mm_struct *mm, char __user *buf, if (env_start != arg_end || env_start >= env_end) env_start = env_end = arg_end; + /* .. and limit it to a maximum of one page of slop */ + if (env_end >= arg_end + PAGE_SIZE) + env_end = arg_end + PAGE_SIZE - 1; + /* We're not going to care if "*ppos" has high bits set */ pos = arg_start + *ppos; @@ -254,10 +258,19 @@ static ssize_t get_mm_cmdline(struct mm_struct *mm, char __user *buf, while (count) { int got; size_t size = min_t(size_t, PAGE_SIZE, count); + long offset; - got = access_remote_vm(mm, pos, page, size, FOLL_ANON); - if (got <= 0) + /* + * Are we already starting past the official end? + * We always include the last byte that is *supposed* + * to be NUL + */ + offset = (pos >= arg_end) ? pos - arg_end + 1 : 0; + + got = access_remote_vm(mm, pos - offset, page, size + offset, FOLL_ANON); + if (got <= offset) break; + got -= offset; /* Don't walk past a NUL character once you hit arg_end */ if (pos + got >= arg_end) { @@ -276,12 +289,17 @@ static ssize_t get_mm_cmdline(struct mm_struct *mm, char __user *buf, n = arg_end - pos - 1; /* Cut off at first NUL after 'n' */ - got = n + strnlen(page+n, got-n); - if (!got) + got = n + strnlen(page+n, offset+got-n); + if (got < offset) break; + got -= offset; + + /* Include the NUL if it existed */ + if (got < size) + got++; } - got -= copy_to_user(buf, page, got); + got -= copy_to_user(buf, page+offset, got); if (unlikely(!got)) { if (!len) len = -EFAULT; |