* [PATCH v2 0/4] Add overflow checks for several syscalls
@ 2023-01-16 11:58 Wupeng Ma
2023-01-16 11:58 ` [PATCH v2 1/4] mm/mlock: return EINVAL if len overflows for mlock/munlock Wupeng Ma
` (3 more replies)
0 siblings, 4 replies; 7+ messages in thread
From: Wupeng Ma @ 2023-01-16 11:58 UTC (permalink / raw)
To: akpm; +Cc: linux-mm, linux-kernel, mawupeng1, kuleshovmail, aneesh.kumar
From: Ma Wupeng <mawupeng1@huawei.com>
While testing mlock, we have a problem if the len of mlock is ULONG_MAX.
The return value of mlock is zero. But nothing will be locked since the
len in do_mlock overflows to zero due to the following code in mlock:
len = PAGE_ALIGN(len + (offset_in_page(start)));
The same problem happens in munlock.
Add new check and return -EINVAL to fix this overflowing scenarios since
they are absolutely wrong.
Similar logic is used to fix problems with multiple syscalls.
Changelog since v1[1]:
- only check overflow rather than access_ok to keep backward-compatibility
[1]: https://lore.kernel.org/lkml/20221228141701.c64add46c4b09aa17f605baf@linux-foundation.org/T/
Ma Wupeng (4):
mm/mlock: return EINVAL if len overflows for mlock/munlock
mm/mempolicy: return EINVAL for if len overflows for
set_mempolicy_home_node
mm/mempolicy: return EINVAL if len overflows for mbind
mm/msync: return ENOMEM if len overflows for msync
mm/mempolicy.c | 6 ++++--
mm/mlock.c | 8 ++++++++
mm/msync.c | 3 ++-
3 files changed, 14 insertions(+), 3 deletions(-)
--
2.25.1
^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH v2 1/4] mm/mlock: return EINVAL if len overflows for mlock/munlock
2023-01-16 11:58 [PATCH v2 0/4] Add overflow checks for several syscalls Wupeng Ma
@ 2023-01-16 11:58 ` Wupeng Ma
2023-01-16 20:51 ` Andrew Morton
2023-01-16 11:58 ` [PATCH v2 2/4] mm/mempolicy: return EINVAL for if len overflows for set_mempolicy_home_node Wupeng Ma
` (2 subsequent siblings)
3 siblings, 1 reply; 7+ messages in thread
From: Wupeng Ma @ 2023-01-16 11:58 UTC (permalink / raw)
To: akpm; +Cc: linux-mm, linux-kernel, mawupeng1, kuleshovmail, aneesh.kumar
From: Ma Wupeng <mawupeng1@huawei.com>
While testing mlock, we have a problem if the len of mlock is ULONG_MAX.
The return value of mlock is zero. But nothing will be locked since the
len in do_mlock overflows to zero due to the following code in mlock:
len = PAGE_ALIGN(len + (offset_in_page(start)));
The same problem happens in munlock.
Add new check and return -EINVAL to fix this overflowing scenarios since
they are absolutely wrong.
Signed-off-by: Ma Wupeng <mawupeng1@huawei.com>
---
mm/mlock.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/mm/mlock.c b/mm/mlock.c
index 7032f6dd0ce1..5a4e767feb28 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -569,6 +569,7 @@ static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t fla
unsigned long locked;
unsigned long lock_limit;
int error = -ENOMEM;
+ size_t old_len = len;
start = untagged_addr(start);
@@ -578,6 +579,9 @@ static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t fla
len = PAGE_ALIGN(len + (offset_in_page(start)));
start &= PAGE_MASK;
+ if (old_len != 0 && len == 0)
+ return -EINVAL;
+
lock_limit = rlimit(RLIMIT_MEMLOCK);
lock_limit >>= PAGE_SHIFT;
locked = len >> PAGE_SHIFT;
@@ -632,12 +636,16 @@ SYSCALL_DEFINE3(mlock2, unsigned long, start, size_t, len, int, flags)
SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len)
{
int ret;
+ size_t old_len = len;
start = untagged_addr(start);
len = PAGE_ALIGN(len + (offset_in_page(start)));
start &= PAGE_MASK;
+ if (old_len != 0 && len == 0)
+ return -EINVAL;
+
if (mmap_write_lock_killable(current->mm))
return -EINTR;
ret = apply_vma_lock_flags(start, len, 0);
--
2.25.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH v2 2/4] mm/mempolicy: return EINVAL for if len overflows for set_mempolicy_home_node
2023-01-16 11:58 [PATCH v2 0/4] Add overflow checks for several syscalls Wupeng Ma
2023-01-16 11:58 ` [PATCH v2 1/4] mm/mlock: return EINVAL if len overflows for mlock/munlock Wupeng Ma
@ 2023-01-16 11:58 ` Wupeng Ma
2023-01-16 11:58 ` [PATCH v2 3/4] mm/mempolicy: return EINVAL if len overflows for mbind Wupeng Ma
2023-01-16 11:58 ` [PATCH v2 4/4] mm/msync: return ENOMEM if len overflows for msync Wupeng Ma
3 siblings, 0 replies; 7+ messages in thread
From: Wupeng Ma @ 2023-01-16 11:58 UTC (permalink / raw)
To: akpm; +Cc: linux-mm, linux-kernel, mawupeng1, kuleshovmail, aneesh.kumar
From: Ma Wupeng <mawupeng1@huawei.com>
Return -EINVAL if len overflows for set_mempolicy_home_node.
Signed-off-by: Ma Wupeng <mawupeng1@huawei.com>
---
mm/mempolicy.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 02c8a712282f..153fda1ebb9c 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1488,6 +1488,7 @@ SYSCALL_DEFINE4(set_mempolicy_home_node, unsigned long, start, unsigned long, le
unsigned long, home_node, unsigned long, flags)
{
struct mm_struct *mm = current->mm;
+ unsigned long old_len = len;
struct vm_area_struct *vma;
struct mempolicy *new;
unsigned long vmstart;
@@ -1515,7 +1516,7 @@ SYSCALL_DEFINE4(set_mempolicy_home_node, unsigned long, start, unsigned long, le
len = PAGE_ALIGN(len);
end = start + len;
- if (end < start)
+ if (end < start || (old_len != 0 && len == 0))
return -EINVAL;
if (end == start)
return 0;
--
2.25.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH v2 3/4] mm/mempolicy: return EINVAL if len overflows for mbind
2023-01-16 11:58 [PATCH v2 0/4] Add overflow checks for several syscalls Wupeng Ma
2023-01-16 11:58 ` [PATCH v2 1/4] mm/mlock: return EINVAL if len overflows for mlock/munlock Wupeng Ma
2023-01-16 11:58 ` [PATCH v2 2/4] mm/mempolicy: return EINVAL for if len overflows for set_mempolicy_home_node Wupeng Ma
@ 2023-01-16 11:58 ` Wupeng Ma
2023-01-16 11:58 ` [PATCH v2 4/4] mm/msync: return ENOMEM if len overflows for msync Wupeng Ma
3 siblings, 0 replies; 7+ messages in thread
From: Wupeng Ma @ 2023-01-16 11:58 UTC (permalink / raw)
To: akpm; +Cc: linux-mm, linux-kernel, mawupeng1, kuleshovmail, aneesh.kumar
From: Ma Wupeng <mawupeng1@huawei.com>
Return -EINVAL if len overflows for mbind.
Signed-off-by: Ma Wupeng <mawupeng1@huawei.com>
---
mm/mempolicy.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 153fda1ebb9c..4cb19a6e368b 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1258,6 +1258,7 @@ static long do_mbind(unsigned long start, unsigned long len,
nodemask_t *nmask, unsigned long flags)
{
struct mm_struct *mm = current->mm;
+ unsigned long old_len = len;
struct mempolicy *new;
unsigned long end;
int err;
@@ -1278,7 +1279,7 @@ static long do_mbind(unsigned long start, unsigned long len,
len = PAGE_ALIGN(len);
end = start + len;
- if (end < start)
+ if (end < start || (old_len != 0 && len == 0))
return -EINVAL;
if (end == start)
return 0;
--
2.25.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH v2 4/4] mm/msync: return ENOMEM if len overflows for msync
2023-01-16 11:58 [PATCH v2 0/4] Add overflow checks for several syscalls Wupeng Ma
` (2 preceding siblings ...)
2023-01-16 11:58 ` [PATCH v2 3/4] mm/mempolicy: return EINVAL if len overflows for mbind Wupeng Ma
@ 2023-01-16 11:58 ` Wupeng Ma
3 siblings, 0 replies; 7+ messages in thread
From: Wupeng Ma @ 2023-01-16 11:58 UTC (permalink / raw)
To: akpm; +Cc: linux-mm, linux-kernel, mawupeng1, kuleshovmail, aneesh.kumar
From: Ma Wupeng <mawupeng1@huawei.com>
Return -ENOMEM if len overflows for msync.
Signed-off-by: Ma Wupeng <mawupeng1@huawei.com>
---
mm/msync.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/msync.c b/mm/msync.c
index ac4c9bfea2e7..8ac227ec38af 100644
--- a/mm/msync.c
+++ b/mm/msync.c
@@ -36,6 +36,7 @@ SYSCALL_DEFINE3(msync, unsigned long, start, size_t, len, int, flags)
struct vm_area_struct *vma;
int unmapped_error = 0;
int error = -EINVAL;
+ size_t old_len = len;
start = untagged_addr(start);
@@ -48,7 +49,7 @@ SYSCALL_DEFINE3(msync, unsigned long, start, size_t, len, int, flags)
error = -ENOMEM;
len = (len + ~PAGE_MASK) & PAGE_MASK;
end = start + len;
- if (end < start)
+ if (end < start || (old_len != 0 && len == 0))
goto out;
error = 0;
if (end == start)
--
2.25.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH v2 1/4] mm/mlock: return EINVAL if len overflows for mlock/munlock
2023-01-16 11:58 ` [PATCH v2 1/4] mm/mlock: return EINVAL if len overflows for mlock/munlock Wupeng Ma
@ 2023-01-16 20:51 ` Andrew Morton
2023-01-17 7:09 ` mawupeng
0 siblings, 1 reply; 7+ messages in thread
From: Andrew Morton @ 2023-01-16 20:51 UTC (permalink / raw)
To: Wupeng Ma; +Cc: linux-mm, linux-kernel, kuleshovmail, aneesh.kumar
On Mon, 16 Jan 2023 19:58:10 +0800 Wupeng Ma <mawupeng1@huawei.com> wrote:
> From: Ma Wupeng <mawupeng1@huawei.com>
>
> While testing mlock, we have a problem if the len of mlock is ULONG_MAX.
> The return value of mlock is zero. But nothing will be locked since the
> len in do_mlock overflows to zero due to the following code in mlock:
>
> len = PAGE_ALIGN(len + (offset_in_page(start)));
>
> The same problem happens in munlock.
>
> Add new check and return -EINVAL to fix this overflowing scenarios since
> they are absolutely wrong.
>
> ...
>
> --- a/mm/mlock.c
> +++ b/mm/mlock.c
> @@ -569,6 +569,7 @@ static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t fla
> unsigned long locked;
> unsigned long lock_limit;
> int error = -ENOMEM;
> + size_t old_len = len;
I'm not sure that "old_len" is a good identifier. It reads to me like
"the length of the old mlocked region" or something.
I really don't like it when functions modify the values of the incoming
argument like this. It would be better to leave `len' alone and create
a new_len or something.
> start = untagged_addr(start);
>
> @@ -578,6 +579,9 @@ static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t fla
> len = PAGE_ALIGN(len + (offset_in_page(start)));
> start &= PAGE_MASK;
>
> + if (old_len != 0 && len == 0)
> + return -EINVAL;
It would be clearer to do this immediately after calculating the new
value of `len'. Before going on to play with `start'.
Can we do something like this?
--- a/mm/mlock.c~a
+++ a/mm/mlock.c
@@ -575,7 +575,12 @@ static __must_check int do_mlock(unsigne
if (!can_do_mlock())
return -EPERM;
- len = PAGE_ALIGN(len + (offset_in_page(start)));
+ if (len) {
+ len = PAGE_ALIGN(len + (offset_in_page(start)));
+ if (len == 0) /* overflow */
+ return -EINVAL;
+ }
+
start &= PAGE_MASK;
lock_limit = rlimit(RLIMIT_MEMLOCK);
_
That depends on how we handle len==0. afaict, mlock(len==0) will
presently burn a bunch of cpu cycles (not that we want to optimize this
case), do nothing then return 0?
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2 1/4] mm/mlock: return EINVAL if len overflows for mlock/munlock
2023-01-16 20:51 ` Andrew Morton
@ 2023-01-17 7:09 ` mawupeng
0 siblings, 0 replies; 7+ messages in thread
From: mawupeng @ 2023-01-17 7:09 UTC (permalink / raw)
To: akpm; +Cc: mawupeng1, linux-mm, linux-kernel, kuleshovmail, aneesh.kumar
On 2023/1/17 4:51, Andrew Morton wrote:
> On Mon, 16 Jan 2023 19:58:10 +0800 Wupeng Ma <mawupeng1@huawei.com> wrote:
>
>> From: Ma Wupeng <mawupeng1@huawei.com>
>>
>> While testing mlock, we have a problem if the len of mlock is ULONG_MAX.
>> The return value of mlock is zero. But nothing will be locked since the
>> len in do_mlock overflows to zero due to the following code in mlock:
>>
>> len = PAGE_ALIGN(len + (offset_in_page(start)));
>>
>> The same problem happens in munlock.
>>
>> Add new check and return -EINVAL to fix this overflowing scenarios since
>> they are absolutely wrong.
>>
>> ...
>>
>> --- a/mm/mlock.c
>> +++ b/mm/mlock.c
>> @@ -569,6 +569,7 @@ static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t fla
>> unsigned long locked;
>> unsigned long lock_limit;
>> int error = -ENOMEM;
>> + size_t old_len = len;
>
> I'm not sure that "old_len" is a good identifier. It reads to me like
> "the length of the old mlocked region" or something.
>
> I really don't like it when functions modify the values of the incoming
> argument like this. It would be better to leave `len' alone and create
> a new_len or something.
Thanks for your reviewing.
You do have a point in saying that.
>
>> start = untagged_addr(start);
>>
>> @@ -578,6 +579,9 @@ static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t fla
>> len = PAGE_ALIGN(len + (offset_in_page(start)));
>> start &= PAGE_MASK;
>>
>> + if (old_len != 0 && len == 0)
>> + return -EINVAL;
>
> It would be clearer to do this immediately after calculating the new
> value of `len'. Before going on to play with `start'.
>
> Can we do something like this?
>
> --- a/mm/mlock.c~a
> +++ a/mm/mlock.c
> @@ -575,7 +575,12 @@ static __must_check int do_mlock(unsigne
> if (!can_do_mlock())
> return -EPERM;
>
> - len = PAGE_ALIGN(len + (offset_in_page(start)));
> + if (len) {
> + len = PAGE_ALIGN(len + (offset_in_page(start)));
> + if (len == 0) /* overflow */
> + return -EINVAL;
> + }
> +
> start &= PAGE_MASK;
>
> lock_limit = rlimit(RLIMIT_MEMLOCK);
> _
It's really more appropriate to check like this, I will use this in the next patchset.
>
> That depends on how we handle len==0. afaict, mlock(len==0) will
> presently burn a bunch of cpu cycles (not that we want to optimize this
> case), do nothing then return 0?
We can add and a new check in if len == 0, since the similar check appears in
mbind, set_mempolicy_home_node, msync.
The origin len == 0 check for mlock/munlock can be found in apply_vma_lock_flags,
We can move this check to here to avoid burn a bunch of cpu cycles.
do_mlock
apply_vma_lock_flags
end = start + len;
if (end == start)
return 0;
Can we do something like this?
diff --git a/mm/mlock.c b/mm/mlock.c
index 7032f6dd0ce1..50a33abc1a2e 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -478,8 +478,6 @@ static int apply_vma_lock_flags(unsigned long start, size_t len,
end = start + len;
if (end < start)
return -EINVAL;
- if (end == start)
- return 0;
vma = mas_walk(&mas);
if (!vma)
return -ENOMEM;
@@ -575,7 +573,12 @@ static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t fla
if (!can_do_mlock())
return -EPERM;
+ if (!len)
+ return 0;
len = PAGE_ALIGN(len + (offset_in_page(start)));
+ if (len == 0)
+ return -EINVAL;
+
start &= PAGE_MASK;
lock_limit = rlimit(RLIMIT_MEMLOCK);
@@ -632,10 +635,14 @@ SYSCALL_DEFINE3(mlock2, unsigned long, start, size_t, len, int, flags)
SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len)
{
int ret;
-
start = untagged_addr(start);
+ if (!len)
+ return 0;
len = PAGE_ALIGN(len + (offset_in_page(start)));
+ if (len == 0)
+ return -EINVAL;
+
start &= PAGE_MASK;
if (mmap_write_lock_killable(current->mm))
>
^ permalink raw reply related [flat|nested] 7+ messages in thread
end of thread, other threads:[~2023-01-17 7:09 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-01-16 11:58 [PATCH v2 0/4] Add overflow checks for several syscalls Wupeng Ma
2023-01-16 11:58 ` [PATCH v2 1/4] mm/mlock: return EINVAL if len overflows for mlock/munlock Wupeng Ma
2023-01-16 20:51 ` Andrew Morton
2023-01-17 7:09 ` mawupeng
2023-01-16 11:58 ` [PATCH v2 2/4] mm/mempolicy: return EINVAL for if len overflows for set_mempolicy_home_node Wupeng Ma
2023-01-16 11:58 ` [PATCH v2 3/4] mm/mempolicy: return EINVAL if len overflows for mbind Wupeng Ma
2023-01-16 11:58 ` [PATCH v2 4/4] mm/msync: return ENOMEM if len overflows for msync Wupeng Ma
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