From e873c74132f0c5f1452816cd9bb26208f0bba1e1 Mon Sep 17 00:00:00 2001 From: Shivank Garg Date: Sat, 22 Aug 2026 19:22:05 +0000 Subject: dmaengine: fix use-after-free in dma_chan_put() and dma_release_channel() When dma_device_put() drops the last reference on chan->device->ref, dma_device_release() runs and may free the dma_device along with its channels. dma_chan_put() then still reads chan->device->owner via dma_chan_to_owner() for the trailing module_put(). KASAN catches it: slab-use-after-free in dma_chan_put+0x3e6/0x4c0 Read of size 8 by task insmod/6319 Freed by task 6319: kfree+0x225/0x470 dma_chan_put+0x395/0x4c0 dmaengine_put+0xf8/0x160 Cache the module owner in dma_chan_put() before the put so the trailing module_put() does not need chan->device. Fixes: 8ad342a86359 ("dmaengine: Add reference counting to dma_device struct") Suggested-by: Sashiko Link: https://sashiko.dev/#/patchset/20260518-dmaengine-kref-fix-v1-1-4d6125048fb7@amd.com Reviewed-by: Frank Li Reviewed-by: Logan Gunthorpe Signed-off-by: Shivank Garg Link: https://patch.msgid.link/20260822-dmaengine-kref-fix-v5-3-d4a4ee47d927@amd.com Signed-off-by: Vinod Koul --- include/asm-generic/pgtable_uffd.h | 83 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 83 insertions(+) create mode 100644 include/asm-generic/pgtable_uffd.h (limited to 'include/asm-generic/pgtable_uffd.h') diff --git a/include/asm-generic/pgtable_uffd.h b/include/asm-generic/pgtable_uffd.h new file mode 100644 index 000000000..30e88fc1d --- /dev/null +++ b/include/asm-generic/pgtable_uffd.h @@ -0,0 +1,83 @@ +#ifndef _ASM_GENERIC_PGTABLE_UFFD_H +#define _ASM_GENERIC_PGTABLE_UFFD_H + +/* + * Some platforms can customize the uffd PTE bit, making it unavailable + * even if the architecture provides the resource. + * Adding this API allows architectures to add their own checks for the + * devices on which the kernel is running. + * Note: When overriding it, please make sure the + * CONFIG_HAVE_ARCH_USERFAULTFD_WP is part of this macro. + */ +#ifndef pgtable_supports_uffd +#define pgtable_supports_uffd() IS_ENABLED(CONFIG_HAVE_ARCH_USERFAULTFD_WP) +#endif + +static inline bool uffd_supports_wp_marker(void) +{ + return pgtable_supports_uffd() && IS_ENABLED(CONFIG_PTE_MARKER_UFFD_WP); +} + +#ifndef CONFIG_HAVE_ARCH_USERFAULTFD_WP +static __always_inline int pte_uffd(pte_t pte) +{ + return 0; +} + +static __always_inline int pmd_uffd(pmd_t pmd) +{ + return 0; +} + +static __always_inline pte_t pte_mkuffd(pte_t pte) +{ + return pte; +} + +static __always_inline pmd_t pmd_mkuffd(pmd_t pmd) +{ + return pmd; +} + +static __always_inline pte_t pte_clear_uffd(pte_t pte) +{ + return pte; +} + +static __always_inline pmd_t pmd_clear_uffd(pmd_t pmd) +{ + return pmd; +} + +static __always_inline pte_t pte_swp_mkuffd(pte_t pte) +{ + return pte; +} + +static __always_inline int pte_swp_uffd(pte_t pte) +{ + return 0; +} + +static __always_inline pte_t pte_swp_clear_uffd(pte_t pte) +{ + return pte; +} + +static inline pmd_t pmd_swp_mkuffd(pmd_t pmd) +{ + return pmd; +} + +static inline int pmd_swp_uffd(pmd_t pmd) +{ + return 0; +} + +static inline pmd_t pmd_swp_clear_uffd(pmd_t pmd) +{ + return pmd; +} +#endif /* CONFIG_HAVE_ARCH_USERFAULTFD_WP */ + +#endif /* _ASM_GENERIC_PGTABLE_UFFD_H */ -- cgit v1.3.1