* + proc-use-untagged_addr-for-pagemap_read-addresses.patch added to -mm tree
@ 2020-12-05 5:23 akpm
0 siblings, 0 replies; 4+ messages in thread
From: akpm @ 2020-12-05 5:23 UTC (permalink / raw)
To: adobriyan, andreyknvl, aryabinin, catalin.marinas, dvyukov,
ebiederm, elver, glider, miles.chen, mm-commits, song.bao.hua,
stable, vincenzo.frascino, will
The patch titled
Subject: proc: use untagged_addr() for pagemap_read addresses
has been added to the -mm tree. Its filename is
proc-use-untagged_addr-for-pagemap_read-addresses.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/proc-use-untagged_addr-for-pagemap_read-addresses.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/proc-use-untagged_addr-for-pagemap_read-addresses.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Miles Chen <miles.chen@mediatek.com>
Subject: proc: use untagged_addr() for pagemap_read addresses
When we try to visit the pagemap of a tagged userspace pointer, we find
that the start_vaddr is not correct because of the tag.
To fix it, we should untag the userspace pointers in pagemap_read().
I tested with 5.10-rc4 and the issue remains.
Explanation from Catalin in [1]:
:Arguably, that's a user-space bug since tagged file offsets were never
:supported. In this case it's not even a tag at bit 56 as per the arm64
:tagged address ABI but rather down to bit 47. You could say that the
:problem is caused by the C library (malloc()) or whoever created the
:tagged vaddr and passed it to this function. It's not a kernel
:regression as we've never supported it.
:
:Now, pagemap is a special case where the offset is usually not generated
:as a classic file offset but rather derived by shifting a user virtual
:address. I guess we can make a concession for pagemap (only) and allow
:such offset with the tag at bit (56 - PAGE_SHIFT + 3).
My test code is based on [2]:
A userspace pointer which has been tagged by 0xb4: 0xb400007662f541c8
=== userspace program ===
uint64 OsLayer::VirtualToPhysical(void *vaddr) {
uint64 frame, paddr, pfnmask, pagemask;
int pagesize = sysconf(_SC_PAGESIZE);
off64_t off = ((uintptr_t)vaddr) / pagesize * 8; // off = 0xb400007662f541c8 / pagesize * 8 = 0x5a00003b317aa0
int fd = open(kPagemapPath, O_RDONLY);
...
if (lseek64(fd, off, SEEK_SET) != off || read(fd, &frame, 8) != 8) {
int err = errno;
string errtxt = ErrorString(err);
if (fd >= 0)
close(fd);
return 0;
}
...
}
=== kernel fs/proc/task_mmu.c ===
static ssize_t pagemap_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
...
src = *ppos;
svpfn = src / PM_ENTRY_BYTES; // svpfn == 0xb400007662f54
start_vaddr = svpfn << PAGE_SHIFT; // start_vaddr == 0xb400007662f54000
end_vaddr = mm->task_size;
/* watch out for wraparound */
// svpfn == 0xb400007662f54
// (mm->task_size >> PAGE) == 0x8000000
if (svpfn > mm->task_size >> PAGE_SHIFT) // the condition is true because of the tag 0xb4
start_vaddr = end_vaddr;
ret = 0;
while (count && (start_vaddr < end_vaddr)) { // we cannot visit correct entry because start_vaddr is set to end_vaddr
int len;
unsigned long end;
...
}
...
}
[1] https://lore.kernel.org/patchwork/patch/1343258/
[2] https://github.com/stressapptest/stressapptest/blob/master/src/os.cc#L158
Link: https://lkml.kernel.org/r/20201204024347.8295-1-miles.chen@mediatek.com
Signed-off-by: Miles Chen <miles.chen@mediatek.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Will Deacon <will@kernel.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Song Bao Hua (Barry Song) <song.bao.hua@hisilicon.com>
Cc: <stable@vger.kernel.org> [5.4-]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
fs/proc/task_mmu.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
--- a/fs/proc/task_mmu.c~proc-use-untagged_addr-for-pagemap_read-addresses
+++ a/fs/proc/task_mmu.c
@@ -1599,11 +1599,15 @@ static ssize_t pagemap_read(struct file
src = *ppos;
svpfn = src / PM_ENTRY_BYTES;
- start_vaddr = svpfn << PAGE_SHIFT;
end_vaddr = mm->task_size;
/* watch out for wraparound */
- if (svpfn > mm->task_size >> PAGE_SHIFT)
+ start_vaddr = end_vaddr;
+ if (svpfn <= (ULONG_MAX >> PAGE_SHIFT))
+ start_vaddr = untagged_addr(svpfn << PAGE_SHIFT);
+
+ /* Ensure the address is inside the task */
+ if (start_vaddr > mm->task_size)
start_vaddr = end_vaddr;
/*
_
Patches currently in -mm which might be from miles.chen@mediatek.com are
proc-use-untagged_addr-for-pagemap_read-addresses.patch
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: + proc-use-untagged_addr-for-pagemap_read-addresses.patch added to -mm tree
2020-12-02 2:03 ` Miles Chen
@ 2020-12-02 23:34 ` Andrew Morton
0 siblings, 0 replies; 4+ messages in thread
From: Andrew Morton @ 2020-12-02 23:34 UTC (permalink / raw)
To: Miles Chen
Cc: adobriyan, andreyknvl, aryabinin, catalin.marinas, dvyukov,
ebiederm, elver, glider, mm-commits, song.bao.hua, stable,
vincenzo.frascino, will.deacon
On Wed, 2 Dec 2020 10:03:49 +0800 Miles Chen <miles.chen@mediatek.com> wrote:
> On Fri, 2020-11-27 at 19:52 -0800, akpm@linux-foundation.org wrote:
> > The patch titled
> > Subject: proc: use untagged_addr() for pagemap_read addresses
> > has been added to the -mm tree. Its filename is
> > proc-use-untagged_addr-for-pagemap_read-addresses.patch
> >
> > This patch should soon appear at
> > https://ozlabs.org/~akpm/mmots/broken-out/proc-use-untagged_addr-for-pagemap_read-addresses.patch
> > and later at
> > https://ozlabs.org/~akpm/mmotm/broken-out/proc-use-untagged_addr-for-pagemap_read-addresses.patch
> >
> > Before you just go and hit "reply", please:
> > a) Consider who else should be cc'ed
> > b) Prefer to cc a suitable mailing list as well
> > c) Ideally: find the original patch on the mailing list and do a
> > reply-to-all to that, adding suitable additional cc's
> >
> > *** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
> >
> > The -mm tree is included into linux-next and is updated
> > there every 3-4 working days
>
> Sorry for bothering, I checked the next-20201201 tag and the patch in
> next-20201201 is [1], but there is a overflow issue in [1] so I
> submitted v2 [2]. We should take [2], right?
> (the patch in this email is [2] but the patch in next-20201201 is [1])
>
> [1] https://lore.kernel.org/patchwork/patch/1343258/
> [1] https://lore.kernel.org/patchwork/patch/1345874/
>
Yup, I haven't released an -mm snapshot since updating to v2. (Been
waiting for an arm64 situation to settle itself out). Hopefully
today...
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: + proc-use-untagged_addr-for-pagemap_read-addresses.patch added to -mm tree
2020-11-28 3:52 akpm
@ 2020-12-02 2:03 ` Miles Chen
2020-12-02 23:34 ` Andrew Morton
0 siblings, 1 reply; 4+ messages in thread
From: Miles Chen @ 2020-12-02 2:03 UTC (permalink / raw)
To: akpm
Cc: adobriyan, andreyknvl, aryabinin, catalin.marinas, dvyukov,
ebiederm, elver, glider, mm-commits, song.bao.hua, stable,
vincenzo.frascino, will.deacon
On Fri, 2020-11-27 at 19:52 -0800, akpm@linux-foundation.org wrote:
> The patch titled
> Subject: proc: use untagged_addr() for pagemap_read addresses
> has been added to the -mm tree. Its filename is
> proc-use-untagged_addr-for-pagemap_read-addresses.patch
>
> This patch should soon appear at
> https://ozlabs.org/~akpm/mmots/broken-out/proc-use-untagged_addr-for-pagemap_read-addresses.patch
> and later at
> https://ozlabs.org/~akpm/mmotm/broken-out/proc-use-untagged_addr-for-pagemap_read-addresses.patch
>
> Before you just go and hit "reply", please:
> a) Consider who else should be cc'ed
> b) Prefer to cc a suitable mailing list as well
> c) Ideally: find the original patch on the mailing list and do a
> reply-to-all to that, adding suitable additional cc's
>
> *** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
>
> The -mm tree is included into linux-next and is updated
> there every 3-4 working days
Sorry for bothering, I checked the next-20201201 tag and the patch in
next-20201201 is [1], but there is a overflow issue in [1] so I
submitted v2 [2]. We should take [2], right?
(the patch in this email is [2] but the patch in next-20201201 is [1])
[1] https://lore.kernel.org/patchwork/patch/1343258/
[1] https://lore.kernel.org/patchwork/patch/1345874/
>
> ------------------------------------------------------
> From: Miles Chen <miles.chen@mediatek.com>
> Subject: proc: use untagged_addr() for pagemap_read addresses
>
> When we try to visit the pagemap of a tagged userspace pointer, we find
> that the start_vaddr is not correct because of the tag. To fix it, we
> should untag the usespace pointers in pagemap_read().
>
> I tested with 5.10-rc4 and the issue remains.
>
> Explanation from Catalin in [1]:
>
> : Arguably, that's a user-space bug since tagged file offsets were never
> : supported. In this case it's not even a tag at bit 56 as per the arm64
> : tagged address ABI but rather down to bit 47. You could say that the
> : problem is caused by the C library (malloc()) or whoever created the
> : tagged vaddr and passed it to this function. It's not a kernel regression
> : as we've never supported it.
> :
> : Now, pagemap is a special case where the offset is usually not generated
> : as a classic file offset but rather derived by shifting a user virtual
> : address. I guess we can make a concession for pagemap (only) and allow
> : such offset with the tag at bit (56 - PAGE_SHIFT + 3).
>
> My test code is baed on [2]:
>
> A userspace pointer which has been tagged by 0xb4: 0xb400007662f541c8
>
> === userspace program ===
>
> uint64 OsLayer::VirtualToPhysical(void *vaddr) {
> uint64 frame, paddr, pfnmask, pagemask;
> int pagesize = sysconf(_SC_PAGESIZE);
> off64_t off = ((uintptr_t)vaddr) / pagesize * 8; // off = 0xb400007662f541c8 / pagesize * 8 = 0x5a00003b317aa0
> int fd = open(kPagemapPath, O_RDONLY);
> ...
>
> if (lseek64(fd, off, SEEK_SET) != off || read(fd, &frame, 8) != 8) {
> int err = errno;
> string errtxt = ErrorString(err);
> if (fd >= 0)
> close(fd);
> return 0;
> }
> ...
> }
>
> === kernel fs/proc/task_mmu.c ===
>
> static ssize_t pagemap_read(struct file *file, char __user *buf,
> size_t count, loff_t *ppos)
> {
> ...
> src = *ppos;
> svpfn = src / PM_ENTRY_BYTES; // svpfn == 0xb400007662f54
> start_vaddr = svpfn << PAGE_SHIFT; // start_vaddr == 0xb400007662f54000
> end_vaddr = mm->task_size;
>
> /* watch out for wraparound */
> // svpfn == 0xb400007662f54
> // (mm->task_size >> PAGE) == 0x8000000
> if (svpfn > mm->task_size >> PAGE_SHIFT) // the condition is true because of the tag 0xb4
> start_vaddr = end_vaddr;
>
> ret = 0;
> while (count && (start_vaddr < end_vaddr)) { // we cannot visit correct entry because start_vaddr is set to end_vaddr
> int len;
> unsigned long end;
> ...
> }
> ...
> }
>
> [1] https://lore.kernel.org/patchwork/patch/1343258/
> [2] https://github.com/stressapptest/stressapptest/blob/master/src/os.cc#L158
>
> Link: https://lkml.kernel.org/r/20201127050738.14440-1-miles.chen@mediatek.com
> Signed-off-by: Miles Chen <miles.chen@mediatek.com>
> Cc: Alexey Dobriyan <adobriyan@gmail.com>
> Cc: Andrey Konovalov <andreyknvl@google.com>
> Cc: Alexander Potapenko <glider@google.com>
> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Cc: Marco Elver <elver@google.com>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: Eric W. Biederman <ebiederm@xmission.com>
> Cc: Song Bao Hua (Barry Song) <song.bao.hua@hisilicon.com>
> Cc: <stable@vger.kernel.org> [5.4+]
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
>
> fs/proc/task_mmu.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> --- a/fs/proc/task_mmu.c~proc-use-untagged_addr-for-pagemap_read-addresses
> +++ a/fs/proc/task_mmu.c
> @@ -1599,11 +1599,15 @@ static ssize_t pagemap_read(struct file
>
> src = *ppos;
> svpfn = src / PM_ENTRY_BYTES;
> - start_vaddr = svpfn << PAGE_SHIFT;
> end_vaddr = mm->task_size;
>
> /* watch out for wraparound */
> - if (svpfn > mm->task_size >> PAGE_SHIFT)
> + start_vaddr = end_vaddr;
> + if (svpfn < (ULONG_MAX >> PAGE_SHIFT))
> + start_vaddr = untagged_addr(svpfn << PAGE_SHIFT);
> +
> + /* Ensure the address is inside the task */
> + if (start_vaddr > mm->task_size)
> start_vaddr = end_vaddr;
>
> /*
> _
>
> Patches currently in -mm which might be from miles.chen@mediatek.com are
>
> proc-use-untagged_addr-for-pagemap_read-addresses.patch
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* + proc-use-untagged_addr-for-pagemap_read-addresses.patch added to -mm tree
@ 2020-11-28 3:52 akpm
2020-12-02 2:03 ` Miles Chen
0 siblings, 1 reply; 4+ messages in thread
From: akpm @ 2020-11-28 3:52 UTC (permalink / raw)
To: adobriyan, andreyknvl, aryabinin, catalin.marinas, dvyukov,
ebiederm, elver, glider, miles.chen, mm-commits, song.bao.hua,
stable, vincenzo.frascino, will.deacon
The patch titled
Subject: proc: use untagged_addr() for pagemap_read addresses
has been added to the -mm tree. Its filename is
proc-use-untagged_addr-for-pagemap_read-addresses.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/proc-use-untagged_addr-for-pagemap_read-addresses.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/proc-use-untagged_addr-for-pagemap_read-addresses.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Miles Chen <miles.chen@mediatek.com>
Subject: proc: use untagged_addr() for pagemap_read addresses
When we try to visit the pagemap of a tagged userspace pointer, we find
that the start_vaddr is not correct because of the tag. To fix it, we
should untag the usespace pointers in pagemap_read().
I tested with 5.10-rc4 and the issue remains.
Explanation from Catalin in [1]:
: Arguably, that's a user-space bug since tagged file offsets were never
: supported. In this case it's not even a tag at bit 56 as per the arm64
: tagged address ABI but rather down to bit 47. You could say that the
: problem is caused by the C library (malloc()) or whoever created the
: tagged vaddr and passed it to this function. It's not a kernel regression
: as we've never supported it.
:
: Now, pagemap is a special case where the offset is usually not generated
: as a classic file offset but rather derived by shifting a user virtual
: address. I guess we can make a concession for pagemap (only) and allow
: such offset with the tag at bit (56 - PAGE_SHIFT + 3).
My test code is baed on [2]:
A userspace pointer which has been tagged by 0xb4: 0xb400007662f541c8
=== userspace program ===
uint64 OsLayer::VirtualToPhysical(void *vaddr) {
uint64 frame, paddr, pfnmask, pagemask;
int pagesize = sysconf(_SC_PAGESIZE);
off64_t off = ((uintptr_t)vaddr) / pagesize * 8; // off = 0xb400007662f541c8 / pagesize * 8 = 0x5a00003b317aa0
int fd = open(kPagemapPath, O_RDONLY);
...
if (lseek64(fd, off, SEEK_SET) != off || read(fd, &frame, 8) != 8) {
int err = errno;
string errtxt = ErrorString(err);
if (fd >= 0)
close(fd);
return 0;
}
...
}
=== kernel fs/proc/task_mmu.c ===
static ssize_t pagemap_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
...
src = *ppos;
svpfn = src / PM_ENTRY_BYTES; // svpfn == 0xb400007662f54
start_vaddr = svpfn << PAGE_SHIFT; // start_vaddr == 0xb400007662f54000
end_vaddr = mm->task_size;
/* watch out for wraparound */
// svpfn == 0xb400007662f54
// (mm->task_size >> PAGE) == 0x8000000
if (svpfn > mm->task_size >> PAGE_SHIFT) // the condition is true because of the tag 0xb4
start_vaddr = end_vaddr;
ret = 0;
while (count && (start_vaddr < end_vaddr)) { // we cannot visit correct entry because start_vaddr is set to end_vaddr
int len;
unsigned long end;
...
}
...
}
[1] https://lore.kernel.org/patchwork/patch/1343258/
[2] https://github.com/stressapptest/stressapptest/blob/master/src/os.cc#L158
Link: https://lkml.kernel.org/r/20201127050738.14440-1-miles.chen@mediatek.com
Signed-off-by: Miles Chen <miles.chen@mediatek.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Song Bao Hua (Barry Song) <song.bao.hua@hisilicon.com>
Cc: <stable@vger.kernel.org> [5.4+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
fs/proc/task_mmu.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
--- a/fs/proc/task_mmu.c~proc-use-untagged_addr-for-pagemap_read-addresses
+++ a/fs/proc/task_mmu.c
@@ -1599,11 +1599,15 @@ static ssize_t pagemap_read(struct file
src = *ppos;
svpfn = src / PM_ENTRY_BYTES;
- start_vaddr = svpfn << PAGE_SHIFT;
end_vaddr = mm->task_size;
/* watch out for wraparound */
- if (svpfn > mm->task_size >> PAGE_SHIFT)
+ start_vaddr = end_vaddr;
+ if (svpfn < (ULONG_MAX >> PAGE_SHIFT))
+ start_vaddr = untagged_addr(svpfn << PAGE_SHIFT);
+
+ /* Ensure the address is inside the task */
+ if (start_vaddr > mm->task_size)
start_vaddr = end_vaddr;
/*
_
Patches currently in -mm which might be from miles.chen@mediatek.com are
proc-use-untagged_addr-for-pagemap_read-addresses.patch
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2020-12-05 5:24 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-12-05 5:23 + proc-use-untagged_addr-for-pagemap_read-addresses.patch added to -mm tree akpm
-- strict thread matches above, loose matches on Subject: below --
2020-11-28 3:52 akpm
2020-12-02 2:03 ` Miles Chen
2020-12-02 23:34 ` Andrew Morton
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).