From: Thomas Zimmermann <tzimmermann@suse.de> stable inclusion from stable-v6.6.95 commit cc3cc41ed67054a03134bea42408c720eec0fa04 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/ICOXM7 CVE: CVE-2025-38427 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 2f29b5c231011b94007d2c8a6d793992f2275db1 upstream. Apply PCI host-bridge window offsets to screen_info framebuffers. Fixes invalid access to I/O memory. Resources behind a PCI host bridge can be relocated by a certain offset in the kernel's CPU address range used for I/O. The framebuffer memory range stored in screen_info refers to the CPU addresses as seen during boot (where the offset is 0). During boot up, firmware may assign a different memory offset to the PCI host bridge and thereby relocating the framebuffer address of the PCI graphics device as seen by the kernel. The information in screen_info must be updated as well. The helper pcibios_bus_to_resource() performs the relocation of the screen_info's framebuffer resource (given in PCI bus addresses). The result matches the I/O-memory resource of the PCI graphics device (given in CPU addresses). As before, we store away the information necessary to later update the information in screen_info itself. Commit 78aa89d1dfba ("firmware/sysfb: Update screen_info for relocated EFI framebuffers") added the code for updating screen_info. It is based on similar functionality that pre-existed in efifb. Efifb uses a pointer to the PCI resource, while the newer code does a memcpy of the region. Hence efifb sees any updates to the PCI resource and avoids the issue. v3: - Only use struct pci_bus_region for PCI bus addresses (Bjorn) - Clarify address semantics in commit messages and comments (Bjorn) v2: - Fixed tags (Takashi, Ivan) - Updated information on efifb Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com> Reported-by: "Ivan T. Ivanov" <iivanov@suse.de> Closes: https://bugzilla.suse.com/show_bug.cgi?id=1240696 Tested-by: "Ivan T. Ivanov" <iivanov@suse.de> Fixes: 78aa89d1dfba ("firmware/sysfb: Update screen_info for relocated EFI framebuffers") Cc: dri-devel@lists.freedesktop.org Cc: <stable@vger.kernel.org> # v6.9+ Link: https://lore.kernel.org/r/20250528080234.7380-1-tzimmermann@suse.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Pu Lehui <pulehui@huawei.com> --- drivers/video/screen_info_pci.c | 79 +++++++++++++++++++++------------ 1 file changed, 50 insertions(+), 29 deletions(-) diff --git a/drivers/video/screen_info_pci.c b/drivers/video/screen_info_pci.c index 6c5833517141..66bfc1d0a6dc 100644 --- a/drivers/video/screen_info_pci.c +++ b/drivers/video/screen_info_pci.c @@ -7,8 +7,8 @@ static struct pci_dev *screen_info_lfb_pdev; static size_t screen_info_lfb_bar; -static resource_size_t screen_info_lfb_offset; -static struct resource screen_info_lfb_res = DEFINE_RES_MEM(0, 0); +static resource_size_t screen_info_lfb_res_start; // original start of resource +static resource_size_t screen_info_lfb_offset; // framebuffer offset within resource static bool __screen_info_relocation_is_valid(const struct screen_info *si, struct resource *pr) { @@ -31,7 +31,7 @@ void screen_info_apply_fixups(void) if (screen_info_lfb_pdev) { struct resource *pr = &screen_info_lfb_pdev->resource[screen_info_lfb_bar]; - if (pr->start != screen_info_lfb_res.start) { + if (pr->start != screen_info_lfb_res_start) { if (__screen_info_relocation_is_valid(si, pr)) { /* * Only update base if we have an actual @@ -47,46 +47,67 @@ void screen_info_apply_fixups(void) } } +static int __screen_info_lfb_pci_bus_region(const struct screen_info *si, unsigned int type, + struct pci_bus_region *r) +{ + u64 base, size; + + base = __screen_info_lfb_base(si); + if (!base) + return -EINVAL; + + size = __screen_info_lfb_size(si, type); + if (!size) + return -EINVAL; + + r->start = base; + r->end = base + size - 1; + + return 0; +} + static void screen_info_fixup_lfb(struct pci_dev *pdev) { unsigned int type; - struct resource res[SCREEN_INFO_MAX_RESOURCES]; - size_t i, numres; + struct pci_bus_region bus_region; int ret; + struct resource r = { + .flags = IORESOURCE_MEM, + }; + const struct resource *pr; const struct screen_info *si = &screen_info; if (screen_info_lfb_pdev) return; // already found type = screen_info_video_type(si); - if (type != VIDEO_TYPE_EFI) - return; // only applies to EFI + if (!__screen_info_has_lfb(type)) + return; // only applies to EFI; maybe VESA - ret = screen_info_resources(si, res, ARRAY_SIZE(res)); + ret = __screen_info_lfb_pci_bus_region(si, type, &bus_region); if (ret < 0) return; - numres = ret; - for (i = 0; i < numres; ++i) { - struct resource *r = &res[i]; - const struct resource *pr; - - if (!(r->flags & IORESOURCE_MEM)) - continue; - pr = pci_find_resource(pdev, r); - if (!pr) - continue; - - /* - * We've found a PCI device with the framebuffer - * resource. Store away the parameters to track - * relocation of the framebuffer aperture. - */ - screen_info_lfb_pdev = pdev; - screen_info_lfb_bar = pr - pdev->resource; - screen_info_lfb_offset = r->start - pr->start; - memcpy(&screen_info_lfb_res, r, sizeof(screen_info_lfb_res)); - } + /* + * Translate the PCI bus address to resource. Account + * for an offset if the framebuffer is behind a PCI host + * bridge. + */ + pcibios_bus_to_resource(pdev->bus, &r, &bus_region); + + pr = pci_find_resource(pdev, &r); + if (!pr) + return; + + /* + * We've found a PCI device with the framebuffer + * resource. Store away the parameters to track + * relocation of the framebuffer aperture. + */ + screen_info_lfb_pdev = pdev; + screen_info_lfb_bar = pr - pdev->resource; + screen_info_lfb_offset = r.start - pr->start; + screen_info_lfb_res_start = bus_region.start; } DECLARE_PCI_FIXUP_CLASS_HEADER(PCI_ANY_ID, PCI_ANY_ID, PCI_BASE_CLASS_DISPLAY, 16, screen_info_fixup_lfb); -- 2.34.1