[PATCH v2] drm/atomic-helpers: fix uaf in drm_atomic_helper_wait_for_vblanks
To briefly summarize the issues reported by syzbot, there are two task call
stacks
as follows:
Task A Task B
--
drm_atomic_commit
drm_atomic_helper_commit
commit_work
commit_tail
drm_atomic_helper_commit_tail commit_tail
drm_atomic_helper_commit_tail
drm_client_modeset_commit_atomic
drm_atomic_state_default_clear
drm_atomic_helper_wait_for_vblanks
When two prerequisites are met simultaneously, the current issue will be
triggered:
1. There is an overlap in the memory range occupied by the crtcs member set
contained
in the instance state of "struct drm_atomic_state" created by Task A and
Task B
2. The context of drm_atomic_helper_commit_tail() has no lock protection,
resulting
in the instance state->crtcs sub item being released by other task
The solution is to add a lock in drm_atomic_helper_commit_tail() to ensure that
there is no other task interference when accessing the instance state.
Reported-and-tested-by: syzbot+0f999d26a4fd79c3a...@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis
---
drivers/gpu/drm/drm_atomic_helper.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/gpu/drm/drm_atomic_helper.c
b/drivers/gpu/drm/drm_atomic_helper.c
index 39ef0a6addeb..b16ff9020097 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -1743,7 +1743,9 @@ EXPORT_SYMBOL(drm_atomic_helper_wait_for_flip_done);
void drm_atomic_helper_commit_tail(struct drm_atomic_state *old_state)
{
struct drm_device *dev = old_state->dev;
+ static DEFINE_MUTEX(lock);
+ mutex_lock();
drm_atomic_helper_commit_modeset_disables(dev, old_state);
drm_atomic_helper_commit_planes(dev, old_state, 0);
@@ -1757,6 +1759,7 @@ void drm_atomic_helper_commit_tail(struct
drm_atomic_state *old_state)
drm_atomic_helper_wait_for_vblanks(dev, old_state);
drm_atomic_helper_cleanup_planes(dev, old_state);
+ mutex_unlock();
}
EXPORT_SYMBOL(drm_atomic_helper_commit_tail);
--
2.43.0
[PATCH] drm/atomic-helpers: fix uaf in drm_atomic_helper_wait_for_vblanks
To briefly summarize the issues reported by syzbot, there are two task call
stacks
as follows:
Task A Task B
--
drm_atomic_nonblocking_commit drm_atomic_commit
drm_atomic_helper_commit drm_atomic_helper_commit
commit_work
commit_tail
drm_atomic_helper_commit_tail commit_tail
drm_atomic_helper_commit_tail
drm_client_modeset_commit_atomic
drm_atomic_state_default_clear
drm_atomic_helper_wait_for_vblanks
When two prerequisites are met simultaneously, the current issue will be
triggered:
1. There is an overlap in the memory range occupied by the crtcs member set
contained
in the instance state of "struct drm_atomic_state" created by Task A and
Task B
2. The context of drm_atomic_helper_commit_tail() has no lock protection,
resulting
in the instance state->crtcs sub item being released by other task
The solution is to add a lock in drm_atomic_helper_commit_tail() to ensure that
there is no other task interference when accessing the instance state.
Reported-and-tested-by: syzbot+0f999d26a4fd79c3a...@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis
---
drivers/gpu/drm/drm_atomic_helper.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/gpu/drm/drm_atomic_helper.c
b/drivers/gpu/drm/drm_atomic_helper.c
index 39ef0a6addeb..b16ff9020097 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -1743,7 +1743,9 @@ EXPORT_SYMBOL(drm_atomic_helper_wait_for_flip_done);
void drm_atomic_helper_commit_tail(struct drm_atomic_state *old_state)
{
struct drm_device *dev = old_state->dev;
+ static DEFINE_MUTEX(lock);
+ mutex_lock();
drm_atomic_helper_commit_modeset_disables(dev, old_state);
drm_atomic_helper_commit_planes(dev, old_state, 0);
@@ -1757,6 +1759,7 @@ void drm_atomic_helper_commit_tail(struct
drm_atomic_state *old_state)
drm_atomic_helper_wait_for_vblanks(dev, old_state);
drm_atomic_helper_cleanup_planes(dev, old_state);
+ mutex_unlock();
}
EXPORT_SYMBOL(drm_atomic_helper_commit_tail);
--
2.43.0
[PATCH V2] drm/modes: Fix divide error in drm_mode_debug_printmodeline
[Syz Log]
divide error: [#1] PREEMPT SMP KASAN
CPU: 0 PID: 5068 Comm: syz-executor357 Not tainted
6.6.0-syzkaller-16039-gac347a0655db #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google
10/09/2023
RIP: 0010:drm_mode_vrefresh drivers/gpu/drm/drm_modes.c:1303 [inline]
RIP: 0010:drm_mode_debug_printmodeline+0x118/0x4e0
drivers/gpu/drm/drm_modes.c:60
Code: 00 41 0f b7 07 66 83 f8 02 b9 01 00 00 00 0f 43 c8 0f b7 c1 0f af e8 44
89 f0 48 69 c8 e8 03 00 00 89 e8 d1 e8 48 01 c8 31 d2 <48> f7 f5 49 89 c6 eb 0c
e8 fb 07 66 fc eb 05 e8 f4 07 66 fc 48 89
RSP: 0018:c9000391f8d0 EFLAGS: 00010246
RAX: 0001f400 RBX: 888025045000 RCX: 0001f400
RDX: RSI: 8000 RDI: 888025045018
RBP: R08: 8528b9af R09:
R10: c9000391f8a0 R11: f52000723f17 R12: 0080
R13: dc00 R14: 0080 R15: 888025045016
FS: 56932380() GS:8880b980() knlGS:
CS: 0010 DS: ES: CR0: 80050033
CR2: 005fdeb8 CR3: 7fcff000 CR4: 003506f0
DR0: DR1: DR2:
DR3: DR6: fffe0ff0 DR7: 0400
Call Trace:
drm_mode_setcrtc+0x83b/0x1880 drivers/gpu/drm/drm_crtc.c:794
drm_ioctl_kernel+0x362/0x500 drivers/gpu/drm/drm_ioctl.c:792
drm_ioctl+0x636/0xb00 drivers/gpu/drm/drm_ioctl.c:895
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xf8/0x170 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b
[Analysis]
When calculating den in drm_mode_vrefresh(), if the vscan value is too large,
there is a probability of unsigned integer overflow.
[Fix]
Before multiplying by vscan, first check if their product will overflow.
If overflow occurs, return 0 and exit the subsequent process.
Reported-and-tested-by: syzbot+2e93e6fb36e6fdc56...@syzkaller.appspotmail.com
Fixes: ea40d7857d52 ("drm/vkms: fbdev emulation support")
Signed-off-by: Edward Adam Davis
---
drivers/gpu/drm/drm_modes.c | 7 +--
1 file changed, 5 insertions(+), 2 deletion(-)
diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index ac9a406250c5..60739d861da2 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -36,6 +36,7 @@
#include
#include
#include
+#include
#include
#include
@@ -1297,8 +1298,10 @@ int drm_mode_vrefresh(const struct drm_display_mode
*mode)
num *= 2;
if (mode->flags & DRM_MODE_FLAG_DBLSCAN)
den *= 2;
- if (mode->vscan > 1)
- den *= mode->vscan;
+ if (mode->vscan > 1) {
+ if (unlikely(check_mul_overflow(den, mode->vscan, )))
+ return 0;
+ }
return DIV_ROUND_CLOSEST_ULL(mul_u32_u32(num, 1000), den);
}
--
2.25.1
[PATCH] drm/modes: Fix divide error in drm_mode_debug_printmodeline
[Syz Log]
divide error: [#1] PREEMPT SMP KASAN
CPU: 0 PID: 5068 Comm: syz-executor357 Not tainted
6.6.0-syzkaller-16039-gac347a0655db #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google
10/09/2023
RIP: 0010:drm_mode_vrefresh drivers/gpu/drm/drm_modes.c:1303 [inline]
RIP: 0010:drm_mode_debug_printmodeline+0x118/0x4e0
drivers/gpu/drm/drm_modes.c:60
Code: 00 41 0f b7 07 66 83 f8 02 b9 01 00 00 00 0f 43 c8 0f b7 c1 0f af e8 44
89 f0 48 69 c8 e8 03 00 00 89 e8 d1 e8 48 01 c8 31 d2 <48> f7 f5 49 89 c6 eb 0c
e8 fb 07 66 fc eb 05 e8 f4 07 66 fc 48 89
RSP: 0018:c9000391f8d0 EFLAGS: 00010246
RAX: 0001f400 RBX: 888025045000 RCX: 0001f400
RDX: RSI: 8000 RDI: 888025045018
RBP: R08: 8528b9af R09:
R10: c9000391f8a0 R11: f52000723f17 R12: 0080
R13: dc00 R14: 0080 R15: 888025045016
FS: 56932380() GS:8880b980() knlGS:
CS: 0010 DS: ES: CR0: 80050033
CR2: 005fdeb8 CR3: 7fcff000 CR4: 003506f0
DR0: DR1: DR2:
DR3: DR6: fffe0ff0 DR7: 0400
Call Trace:
drm_mode_setcrtc+0x83b/0x1880 drivers/gpu/drm/drm_crtc.c:794
drm_ioctl_kernel+0x362/0x500 drivers/gpu/drm/drm_ioctl.c:792
drm_ioctl+0x636/0xb00 drivers/gpu/drm/drm_ioctl.c:895
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xf8/0x170 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b
[Analysis]
When calculating den in drm_mode_vrefresh(), if the vscan value is too large,
there is a probability of unsigned integer overflow.
[Fix]
Before multiplying by vscan, first determine their ilog2. When their total
exceeds 32, return -EINVAL and exit the subsequent calculation.
Reported-and-tested-by: syzbot+2e93e6fb36e6fdc56...@syzkaller.appspotmail.com
Fixes: ea40d7857d52 ("drm/vkms: fbdev emulation support")
Signed-off-by: Edward Adam Davis
---
drivers/gpu/drm/drm_modes.c | 6 +-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index ac9a406250c5..c7ec1ab041f8 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -36,6 +36,7 @@
#include
#include
#include
+#include
#include
#include
@@ -1297,8 +1298,11 @@ int drm_mode_vrefresh(const struct drm_display_mode
*mode)
num *= 2;
if (mode->flags & DRM_MODE_FLAG_DBLSCAN)
den *= 2;
- if (mode->vscan > 1)
+ if (mode->vscan > 1) {
+ if (ilog2(den) + ilog2(mode->vscan) >= 32)
+ return -EINVAL;
den *= mode->vscan;
+ }
return DIV_ROUND_CLOSEST_ULL(mul_u32_u32(num, 1000), den);
}
--
2.25.1
