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| author |   Mateusz Guzik <mguzik@redhat.com> | 2016-01-20 15:01:05 -0800 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2016-01-20 17:09:18 -0800 |
| commit | a3b609ef9f8b1dbfe97034ccad6cd3fe71fbe7ab (patch) | |
| tree | 0162563ac7cab6364a3ec6df61b4b96a876943f4 | |
| parent | prctl: take mmap sem for writing to protect against others (diff) | |
| download | linux-dev-a3b609ef9f8b1dbfe97034ccad6cd3fe71fbe7ab.tar.xz linux-dev-a3b609ef9f8b1dbfe97034ccad6cd3fe71fbe7ab.zip | |
proc read mm's {arg,env}_{start,end} with mmap semaphore taken.
Only functions doing more than one read are modified. Consumeres
happened to deal with possibly changing data, but it does not seem like
a good thing to rely on.
Signed-off-by: Mateusz Guzik <mguzik@redhat.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Jarod Wilson <jarod@redhat.com>
Cc: Jan Stancek <jstancek@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Anshuman Khandual <anshuman.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | fs/proc/base.c | 13 | ||||
| -rw-r--r-- | mm/util.c | 16 |
2 files changed, 22 insertions, 7 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index e665097c1da5..4f764c2ac1a5 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -953,6 +953,7 @@ static ssize_t environ_read(struct file *file, char __user *buf, unsigned long src = *ppos; int ret = 0; struct mm_struct *mm = file->private_data; + unsigned long env_start, env_end; if (!mm) return 0; @@ -964,19 +965,25 @@ static ssize_t environ_read(struct file *file, char __user *buf, ret = 0; if (!atomic_inc_not_zero(&mm->mm_users)) goto free; + + down_read(&mm->mmap_sem); + env_start = mm->env_start; + env_end = mm->env_end; + up_read(&mm->mmap_sem); + while (count > 0) { size_t this_len, max_len; int retval; - if (src >= (mm->env_end - mm->env_start)) + if (src >= (env_end - env_start)) break; - this_len = mm->env_end - (mm->env_start + src); + this_len = env_end - (env_start + src); max_len = min_t(size_t, PAGE_SIZE, count); this_len = min(max_len, this_len); - retval = access_remote_vm(mm, (mm->env_start + src), + retval = access_remote_vm(mm, (env_start + src), page, this_len, 0); if (retval <= 0) { diff --git a/mm/util.c b/mm/util.c index 6d1f9200f74e..c108a6542d05 100644 --- a/mm/util.c +++ b/mm/util.c @@ -476,17 +476,25 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen) int res = 0; unsigned int len; struct mm_struct *mm = get_task_mm(task); + unsigned long arg_start, arg_end, env_start, env_end; if (!mm) goto out; if (!mm->arg_end) goto out_mm; /* Shh! No looking before we're done */ - len = mm->arg_end - mm->arg_start; + down_read(&mm->mmap_sem); + arg_start = mm->arg_start; + arg_end = mm->arg_end; + env_start = mm->env_start; + env_end = mm->env_end; + up_read(&mm->mmap_sem); + + len = arg_end - arg_start; if (len > buflen) len = buflen; - res = access_process_vm(task, mm->arg_start, buffer, len, 0); + res = access_process_vm(task, arg_start, buffer, len, 0); /* * If the nul at the end of args has been overwritten, then @@ -497,10 +505,10 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen) if (len < res) { res = len; } else { - len = mm->env_end - mm->env_start; + len = env_end - env_start; if (len > buflen - res) len = buflen - res; - res += access_process_vm(task, mm->env_start, + res += access_process_vm(task, env_start, buffer+res, len, 0); res = strnlen(buffer, res); } |