From 543e8669ed9bfb30545fd52bc0e047ca4df7fb31 Mon Sep 17 00:00:00 2001 From: Peilin Ye Date: Tue, 28 Jul 2020 15:29:24 -0400 Subject: drm/amdgpu: Prevent kernel-infoleak in amdgpu_info_ioctl() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Compiler leaves a 4-byte hole near the end of `dev_info`, causing amdgpu_info_ioctl() to copy uninitialized kernel stack memory to userspace when `size` is greater than 356. In 2015 we tried to fix this issue by doing `= {};` on `dev_info`, which unfortunately does not initialize that 4-byte hole. Fix it by using memset() instead. Cc: stable@vger.kernel.org Fixes: c193fa91b918 ("drm/amdgpu: information leak in amdgpu_info_ioctl()") Fixes: d38ceaf99ed0 ("drm/amdgpu: add core driver (v4)") Suggested-by: Dan Carpenter Reviewed-by: Christian König Signed-off-by: Peilin Ye Signed-off-by: Alex Deucher --- drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'drivers') diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c index d7e17e34fee1..21292098bc02 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c @@ -692,9 +692,10 @@ static int amdgpu_info_ioctl(struct drm_device *dev, void *data, struct drm_file return n ? -EFAULT : 0; } case AMDGPU_INFO_DEV_INFO: { - struct drm_amdgpu_info_device dev_info = {}; + struct drm_amdgpu_info_device dev_info; uint64_t vm_size; + memset(&dev_info, 0, sizeof(dev_info)); dev_info.device_id = dev->pdev->device; dev_info.chip_rev = adev->rev_id; dev_info.external_rev = adev->external_rev_id; -- cgit v1.2.3 From fde9f39ac7f1ffd799a96ffa1e06b2051f0898f1 Mon Sep 17 00:00:00 2001 From: Mazin Rezk Date: Mon, 27 Jul 2020 05:40:46 +0000 Subject: drm/amd/display: Clear dm_state for fast updates This patch fixes a race condition that causes a use-after-free during amdgpu_dm_atomic_commit_tail. This can occur when 2 non-blocking commits are requested and the second one finishes before the first. Essentially, this bug occurs when the following sequence of events happens: 1. Non-blocking commit #1 is requested w/ a new dm_state #1 and is deferred to the workqueue. 2. Non-blocking commit #2 is requested w/ a new dm_state #2 and is deferred to the workqueue. 3. Commit #2 starts before commit #1, dm_state #1 is used in the commit_tail and commit #2 completes, freeing dm_state #1. 4. Commit #1 starts after commit #2 completes, uses the freed dm_state 1 and dereferences a freelist pointer while setting the context. Since this bug has only been spotted with fast commits, this patch fixes the bug by clearing the dm_state instead of using the old dc_state for fast updates. In addition, since dm_state is only used for its dc_state and amdgpu_dm_atomic_commit_tail will retain the dc_state if none is found, removing the dm_state should not have any consequences in fast updates. This use-after-free bug has existed for a while now, but only caused a noticeable issue starting from 5.7-rc1 due to 3202fa62f ("slub: relocate freelist pointer to middle of object") moving the freelist pointer from dm_state->base (which was unused) to dm_state->context (which is dereferenced). Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=207383 Fixes: bd200d190f45 ("drm/amd/display: Don't replace the dc_state for fast updates") Reported-by: Duncan <1i5t5.duncan@cox.net> Signed-off-by: Mazin Rezk Reviewed-by: Nicholas Kazlauskas Signed-off-by: Alex Deucher Cc: stable@vger.kernel.org --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 36 +++++++++++++++++------ 1 file changed, 27 insertions(+), 9 deletions(-) (limited to 'drivers') diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c index 86ffa0c2880f..710edc70e37e 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -8717,20 +8717,38 @@ static int amdgpu_dm_atomic_check(struct drm_device *dev, * the same resource. If we have a new DC context as part of * the DM atomic state from validation we need to free it and * retain the existing one instead. + * + * Furthermore, since the DM atomic state only contains the DC + * context and can safely be annulled, we can free the state + * and clear the associated private object now to free + * some memory and avoid a possible use-after-free later. */ - struct dm_atomic_state *new_dm_state, *old_dm_state; - new_dm_state = dm_atomic_get_new_state(state); - old_dm_state = dm_atomic_get_old_state(state); + for (i = 0; i < state->num_private_objs; i++) { + struct drm_private_obj *obj = state->private_objs[i].ptr; - if (new_dm_state && old_dm_state) { - if (new_dm_state->context) - dc_release_state(new_dm_state->context); + if (obj->funcs == adev->dm.atomic_obj.funcs) { + int j = state->num_private_objs-1; - new_dm_state->context = old_dm_state->context; + dm_atomic_destroy_state(obj, + state->private_objs[i].state); + + /* If i is not at the end of the array then the + * last element needs to be moved to where i was + * before the array can safely be truncated. + */ + if (i != j) + state->private_objs[i] = + state->private_objs[j]; - if (old_dm_state->context) - dc_retain_state(old_dm_state->context); + state->private_objs[j].ptr = NULL; + state->private_objs[j].state = NULL; + state->private_objs[j].old_state = NULL; + state->private_objs[j].new_state = NULL; + + state->num_private_objs = j; + break; + } } } -- cgit v1.2.3 From 87004abfbc27261edd15716515d89ab42198b405 Mon Sep 17 00:00:00 2001 From: Alex Deucher Date: Thu, 30 Jul 2020 11:02:30 -0400 Subject: Revert "drm/amdgpu: Fix NULL dereference in dpm sysfs handlers" This regressed some working configurations so revert it. Will fix this properly for 5.9 and backport then. This reverts commit 38e0c89a19fd13f28d2b4721035160a3e66e270b. Signed-off-by: Alex Deucher Cc: stable@vger.kernel.org --- drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'drivers') diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c index ebb8a28ff002..02e6f8c4dde0 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c @@ -778,7 +778,8 @@ static ssize_t amdgpu_set_pp_od_clk_voltage(struct device *dev, tmp_str++; while (isspace(*++tmp_str)); - while ((sub_str = strsep(&tmp_str, delimiter)) != NULL) { + while (tmp_str[0]) { + sub_str = strsep(&tmp_str, delimiter); ret = kstrtol(sub_str, 0, ¶meter[parameter_size]); if (ret) return -EINVAL; @@ -1038,7 +1039,8 @@ static ssize_t amdgpu_read_mask(const char *buf, size_t count, uint32_t *mask) memcpy(buf_cpy, buf, bytes); buf_cpy[bytes] = '\0'; tmp = buf_cpy; - while ((sub_str = strsep(&tmp, delimiter)) != NULL) { + while (tmp[0]) { + sub_str = strsep(&tmp, delimiter); if (strlen(sub_str)) { ret = kstrtol(sub_str, 0, &level); if (ret) @@ -1635,7 +1637,8 @@ static ssize_t amdgpu_set_pp_power_profile_mode(struct device *dev, i++; memcpy(buf_cpy, buf, count-i); tmp_str = buf_cpy; - while ((sub_str = strsep(&tmp_str, delimiter)) != NULL) { + while (tmp_str[0]) { + sub_str = strsep(&tmp_str, delimiter); ret = kstrtol(sub_str, 0, ¶meter[parameter_size]); if (ret) return -EINVAL; -- cgit v1.2.3