FAILED: patch "[PATCH] resource: fix region_intersects() vs" failed to apply to 5.10-stable tree
[email protected]
maintainerThe patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x b4afe4183ec77f230851ea139d91e5cf2644c68b
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024100732-disinfect-spied-83fc@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..
Possible dependencies:
b4afe4183ec7 ("resource: fix region_intersects() vs add_memory_driver_managed()") 14b80582c43e ("resource: Introduce alloc_free_mem_region()") 27674ef6c73f ("mm: remove the extra ZONE_DEVICE struct page refcount") dc90f0846df4 ("mm: don't include <linux/memremap.h> in <linux/mm.h>") 895749455f60 ("mm: simplify freeing of devmap managed pages") 75e55d8a107e ("mm: move free_devmap_managed_page to memremap.c") 730ff52194cd ("mm: remove pointless includes from <linux/hmm.h>") f56caedaf94f ("Merge branch 'akpm' (patches from Andrew)")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From b4afe4183ec77f230851ea139d91e5cf2644c68b Mon Sep 17 00:00:00 2001
From: Huang Ying <[email protected]>
Date: Fri, 6 Sep 2024 11:07:11 +0800
Subject: [PATCH] resource: fix region_intersects() vs
add_memory_driver_managed()
On a system with CXL memory, the resource tree (/proc/iomem) related to CXL memory may look like something as follows.
490000000-50fffffff : CXL Window 0
490000000-50fffffff : region0
490000000-50fffffff : dax0.0
490000000-50fffffff : System RAM (kmem)Because drivers/dax/kmem.c calls add_memory_driver_managed() during onlining CXL memory, which makes "System RAM (kmem)" a descendant of "CXL Window X". This confuses region_intersects(), which expects all "System RAM" resources to be at the top level of iomem_resource. This can lead to bugs.
For example, when the following command line is executed to write some memory in CXL memory range via /dev/mem,
$ dd if=data of=/dev/mem bs=$((1 << 10)) seek=$((0x490000000 >> 10)) count=1 dd: error writing '/dev/mem': Bad address 1+0 records in 0+0 records out 0 bytes copied, 0.0283507 s, 0.0 kB/s
the command fails as expected. However, the error code is wrong. It should be "Operation not permitted" instead of "Bad address". More seriously, the /dev/mem permission checking in devmem_is_allowed() passes incorrectly. Although the accessing is prevented later because ioremap() isn't allowed to map system RAM, it is a potential security issue. During command executing, the following warning is reported in the kernel log for calling ioremap() on system RAM.
ioremap on RAM at 0x0000000490000000 - 0x0000000490000fff
WARNING: CPU: 2 PID: 416 at arch/x86/mm/ioremap.c:216 __ioremap_caller.constprop.0+0x131/0x35d Call Trace: memremap+0xcb/0x184 xlate_dev_mem_ptr+0x25/0x2f write_mem+0x94/0xfb vfs_write+0x128/0x26d ksys_write+0xac/0xfe do_syscall_64+0x9a/0xfd entry_SYSCALL_64_after_hwframe+0x4b/0x53
The details of command execution process are as follows. In the above resource tree, "System RAM" is a descendant of "CXL Window 0" instead of a top level resource. So, region_intersects() will report no System RAM resources in the CXL memory region incorrectly, because it only checks the top level resources. Consequently, devmem_is_allowed() will return 1 (allow access via /dev/mem) for CXL memory region incorrectly. Fortunately, ioremap() doesn't allow to map System RAM and reject the access.
So, region_intersects() needs to be fixed to work correctly with the resource tree with "System RAM" not at top level as above. To fix it, if we found a unmatched resource in the top level, we will continue to search matched resources in its descendant resources. So, we will not miss any matched resources in resource tree anymore.
In the new implementation, an example resource tree
|------------- "CXL Window 0" ------------| |-- "System RAM" --|
will behave similar as the following fake resource tree for region_intersects(, IORESOURCE_SYSTEM_RAM, ),
|-- "System RAM" --||-- "CXL Window 0a" --|
Where "CXL Window 0a" is part of the original "CXL Window 0" that isn't covered by "System RAM".
kernel/resource.c +50 -8
@@ -540,20 +540,62 @@ static int __region_intersects(struct resource *parent, resource_size_t start, size_t size, unsigned long flags, unsigned long desc) { - struct resource res; + resource_size_t ostart, oend;int type =0 ;int other =0 ; -struct resource *p; +struct resource *p, *dp; +bool is_type, covered; +struct resource res; res.start = start; res.end = start + size -1 ;for (p = parent->child; p ; p = p->sibling) { -bool is_type = (((p->flags & flags) == flags) && - ((desc ==IORES_DESC_NONE ) || - (desc == p->desc))); - -if (resource_overlaps (p, &res)) - is_type ? type++ : other++; +if (!resource_overlaps (p, &res)) +continue ; + is_type = (p->flags & flags) == flags && + (desc ==IORES_DESC_NONE || desc == p->desc); +if (is_type) { + type++; +continue ; + } +/* +* Continue to search in descendant resources as if the +* matched descendant resources cover some ranges of 'p'. +* +* |------------- "CXL Window 0" ------------| +* |-- "System RAM" --| +* +* will behave similar as the following fake resource +* tree when searching "System RAM". +* +* |-- "System RAM" --||-- "CXL Window 0a" --| +*/ + covered = false; + ostart =max (res.start, p->start); + oend =min (res.end, p->end); +for_each_resource (p, dp, false) { +if (!resource_overlaps (dp, &res)) +continue ; + is_type = (dp->flags & flags) == flags && + (desc ==IORES_DESC_NONE || desc == dp->desc); +if (is_type) { + type++; +/* +* Range from 'ostart' to 'dp->start' +* isn't covered by matched resource. +*/ +if (dp->start > ostart) +break ; +if (dp->end >= oend) { + covered = true; +break ; + } +/* Remove covered range */ + ostart =max (ostart, dp->end +1 ); + } + } +if (!covered) + other++; }if (type ==0 )
PATCH 1/1 resource: fix region_intersects() vs add_memory_driver_managed()
On a system with CXL memory, the resource tree (/proc/iomem) related to CXL memory may look like something as follows.
490000000-50fffffff : CXL Window 0
490000000-50fffffff : region0
490000000-50fffffff : dax0.0
490000000-50fffffff : System RAM (kmem)Because drivers/dax/kmem.c calls add_memory_driver_managed() during onlining CXL memory, which makes "System RAM (kmem)" a descendant of "CXL Window X". This confuses region_intersects(), which expects all "System RAM" resources to be at the top level of iomem_resource. This can lead to bugs.
For example, when the following command line is executed to write some memory in CXL memory range via /dev/mem,
$ dd if=data of=/dev/mem bs=$((1 << 10)) seek=$((0x490000000 >> 10)) count=1 dd: error writing '/dev/mem': Bad address 1+0 records in 0+0 records out 0 bytes copied, 0.0283507 s, 0.0 kB/s
the command fails as expected. However, the error code is wrong. It should be "Operation not permitted" instead of "Bad address". More seriously, the /dev/mem permission checking in devmem_is_allowed() passes incorrectly. Although the accessing is prevented later because ioremap() isn't allowed to map system RAM, it is a potential security issue. During command executing, the following warning is reported in the kernel log for calling ioremap() on system RAM.
ioremap on RAM at 0x0000000490000000 - 0x0000000490000fff
WARNING: CPU: 2 PID: 416 at arch/x86/mm/ioremap.c:216 __ioremap_caller.constprop.0+0x131/0x35d Call Trace: memremap+0xcb/0x184 xlate_dev_mem_ptr+0x25/0x2f write_mem+0x94/0xfb vfs_write+0x128/0x26d ksys_write+0xac/0xfe do_syscall_64+0x9a/0xfd entry_SYSCALL_64_after_hwframe+0x4b/0x53
The details of command execution process are as follows. In the above resource tree, "System RAM" is a descendant of "CXL Window 0" instead of a top level resource. So, region_intersects() will report no System RAM resources in the CXL memory region incorrectly, because it only checks the top level resources. Consequently, devmem_is_allowed() will return 1 (allow access via /dev/mem) for CXL memory region incorrectly. Fortunately, ioremap() doesn't allow to map System RAM and reject the access.
So, region_intersects() needs to be fixed to work correctly with the resource tree with "System RAM" not at top level as above. To fix it, if we found a unmatched resource in the top level, we will continue to search matched resources in its descendant resources. So, we will not miss any matched resources in resource tree anymore.
In the new implementation, an example resource tree
|------------- "CXL Window 0" ------------| |-- "System RAM" --|
will behave similar as the following fake resource tree for region_intersects(, IORESOURCE_SYSTEM_RAM, ),
|-- "System RAM" --||-- "CXL Window 0a" --|
Where "CXL Window 0a" is part of the original "CXL Window 0" that isn't covered by "System RAM".
--- kernel/resource.c | 58 ++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 50 insertions(+), 8 deletions(-)
kernel/resource.c +50 -8
@@ -539,21 +539,63 @@ EXPORT_SYMBOL_GPL(page_is_ram);int region_intersects (resource_size_t start,size_t size,unsigned long flags,unsigned long desc) { -struct resource res; +resource_size_t ostart, oend;int type =0 ;int other =0 ; -struct resource *p; +struct resource *p, *dp; +bool is_type, covered; +struct resource res; res.start = start; res.end = start + size -1 ;read_lock (&resource_lock);for (p = iomem_resource.child; p ; p = p->sibling) { -bool is_type = (((p->flags & flags) == flags) && - ((desc ==IORES_DESC_NONE ) || - (desc == p->desc))); - -if (resource_overlaps (p, &res)) - is_type ? type++ : other++; +if (!resource_overlaps (p, &res)) +continue ; + is_type = (p->flags & flags) == flags && + (desc ==IORES_DESC_NONE || desc == p->desc); +if (is_type) { + type++; +continue ; + } +/* +* Continue to search in descendant resources as if the +* matched descendant resources cover some ranges of 'p'. +* +* |------------- "CXL Window 0" ------------| +* |-- "System RAM" --| +* +* will behave similar as the following fake resource +* tree when searching "System RAM". +* +* |-- "System RAM" --||-- "CXL Window 0a" --| +*/ + covered = false; + ostart =max (res.start, p->start); + oend =min (res.end, p->end); +for (dp = p->child; dp; dp =next_resource (dp, false)) { +if (!resource_overlaps (dp, &res)) +continue ; + is_type = (dp->flags & flags) == flags && + (desc ==IORES_DESC_NONE || desc == dp->desc); +if (is_type) { + type++; +/* +* Range from 'ostart' to 'dp->start' +* isn't covered by matched resource. +*/ +if (dp->start > ostart) +break ; +if (dp->end >= oend) { + covered = true; +break ; + } +/* Remove covered range */ + ostart =max (ostart, dp->end +1 ); + } + } +if (!covered) + other++; }read_unlock (&resource_lock);
Signature · 1 line
2.39.2
Greg KH
maintainerRe: [PATCH 5.10.y] resource: fix region_intersects() vs add_memory_driver_managed()
Quoted 2 lines · Huang Ying
On a system with CXL memory, the resource tree (
/proc/iomem) related to CXL memory may look like something as follows.
<snip>
You forgot to list what the git id of this commit in Linus's tree is :(
Please fix up and resend all backports with that information.
thanks,
greg k-h
Re: [PATCH 5.10.y] resource: fix region_intersects() vs add_memory_driver_managed()
Quoted 7 lines · Greg KH
Quoted 2 lines · Huang Ying
On a system with CXL memory, the resource tree (
/proc/iomem) related to CXL memory may look like something as follows.<snip>
You forgot to list what the git id of this commit in Linus's tree is :(
Sorry about that!
Quoted 1 line
Please fix up and resend all backports with that information.
Sure. Will do that.
--
Best Regards,
Huang, Ying
PATCH 1/1 resource: fix region_intersects() vs add_memory_driver_managed()
In reply to [email protected]commit b4afe4183ec77f230851ea139d91e5cf2644c68b upstream.
On a system with CXL memory, the resource tree (/proc/iomem) related to CXL memory may look like something as follows.
490000000-50fffffff : CXL Window 0
490000000-50fffffff : region0
490000000-50fffffff : dax0.0
490000000-50fffffff : System RAM (kmem)Because drivers/dax/kmem.c calls add_memory_driver_managed() during onlining CXL memory, which makes "System RAM (kmem)" a descendant of "CXL Window X". This confuses region_intersects(), which expects all "System RAM" resources to be at the top level of iomem_resource. This can lead to bugs.
For example, when the following command line is executed to write some memory in CXL memory range via /dev/mem,
$ dd if=data of=/dev/mem bs=$((1 << 10)) seek=$((0x490000000 >> 10)) count=1 dd: error writing '/dev/mem': Bad address 1+0 records in 0+0 records out 0 bytes copied, 0.0283507 s, 0.0 kB/s
the command fails as expected. However, the error code is wrong. It should be "Operation not permitted" instead of "Bad address". More seriously, the /dev/mem permission checking in devmem_is_allowed() passes incorrectly. Although the accessing is prevented later because ioremap() isn't allowed to map system RAM, it is a potential security issue. During command executing, the following warning is reported in the kernel log for calling ioremap() on system RAM.
ioremap on RAM at 0x0000000490000000 - 0x0000000490000fff
WARNING: CPU: 2 PID: 416 at arch/x86/mm/ioremap.c:216 __ioremap_caller.constprop.0+0x131/0x35d Call Trace: memremap+0xcb/0x184 xlate_dev_mem_ptr+0x25/0x2f write_mem+0x94/0xfb vfs_write+0x128/0x26d ksys_write+0xac/0xfe do_syscall_64+0x9a/0xfd entry_SYSCALL_64_after_hwframe+0x4b/0x53
The details of command execution process are as follows. In the above resource tree, "System RAM" is a descendant of "CXL Window 0" instead of a top level resource. So, region_intersects() will report no System RAM resources in the CXL memory region incorrectly, because it only checks the top level resources. Consequently, devmem_is_allowed() will return 1 (allow access via /dev/mem) for CXL memory region incorrectly. Fortunately, ioremap() doesn't allow to map System RAM and reject the access.
So, region_intersects() needs to be fixed to work correctly with the resource tree with "System RAM" not at top level as above. To fix it, if we found a unmatched resource in the top level, we will continue to search matched resources in its descendant resources. So, we will not miss any matched resources in resource tree anymore.
In the new implementation, an example resource tree
|------------- "CXL Window 0" ------------| |-- "System RAM" --|
will behave similar as the following fake resource tree for region_intersects(, IORESOURCE_SYSTEM_RAM, ),
|-- "System RAM" --||-- "CXL Window 0a" --|
Where "CXL Window 0a" is part of the original "CXL Window 0" that isn't covered by "System RAM".
--- kernel/resource.c | 58 ++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 50 insertions(+), 8 deletions(-)
kernel/resource.c +50 -8
@@ -539,21 +539,63 @@ EXPORT_SYMBOL_GPL(page_is_ram);int region_intersects (resource_size_t start,size_t size,unsigned long flags,unsigned long desc) { -struct resource res; +resource_size_t ostart, oend;int type =0 ;int other =0 ; -struct resource *p; +struct resource *p, *dp; +bool is_type, covered; +struct resource res; res.start = start; res.end = start + size -1 ;read_lock (&resource_lock);for (p = iomem_resource.child; p ; p = p->sibling) { -bool is_type = (((p->flags & flags) == flags) && - ((desc ==IORES_DESC_NONE ) || - (desc == p->desc))); - -if (resource_overlaps (p, &res)) - is_type ? type++ : other++; +if (!resource_overlaps (p, &res)) +continue ; + is_type = (p->flags & flags) == flags && + (desc ==IORES_DESC_NONE || desc == p->desc); +if (is_type) { + type++; +continue ; + } +/* +* Continue to search in descendant resources as if the +* matched descendant resources cover some ranges of 'p'. +* +* |------------- "CXL Window 0" ------------| +* |-- "System RAM" --| +* +* will behave similar as the following fake resource +* tree when searching "System RAM". +* +* |-- "System RAM" --||-- "CXL Window 0a" --| +*/ + covered = false; + ostart =max (res.start, p->start); + oend =min (res.end, p->end); +for (dp = p->child; dp; dp =next_resource (dp, false)) { +if (!resource_overlaps (dp, &res)) +continue ; + is_type = (dp->flags & flags) == flags && + (desc ==IORES_DESC_NONE || desc == dp->desc); +if (is_type) { + type++; +/* +* Range from 'ostart' to 'dp->start' +* isn't covered by matched resource. +*/ +if (dp->start > ostart) +break ; +if (dp->end >= oend) { + covered = true; +break ; + } +/* Remove covered range */ + ostart =max (ostart, dp->end +1 ); + } + } +if (!covered) + other++; }read_unlock (&resource_lock);
Signature · 1 line
2.39.2