Messages in this thread | | | Date | Thu, 22 Sep 2022 20:07:44 +0800 | From | Jisheng Zhang <> | Subject | Re: [PATCH v2] riscv: vdso: fix NULL deference in vdso_join_timens() when vfork |
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On Thu, Sep 15, 2022 at 11:02:19AM -0700, Palmer Dabbelt wrote: > On Thu, 08 Sep 2022 08:04:21 PDT (-0700), jszhang@kernel.org wrote: > > Testing tools/testing/selftests/timens/vfork_exec.c got below > > kernel log: > > > > [ 6.838454] Unable to handle kernel access to user memory without uaccess routines at virtual address 0000000000000020 > > [ 6.842255] Oops [#1] > > [ 6.842871] Modules linked in: > > [ 6.844249] CPU: 1 PID: 64 Comm: vfork_exec Not tainted 6.0.0-rc3-rt15+ #8 > > [ 6.845861] Hardware name: riscv-virtio,qemu (DT) > > [ 6.848009] epc : vdso_join_timens+0xd2/0x110 > > [ 6.850097] ra : vdso_join_timens+0xd2/0x110 > > [ 6.851164] epc : ffffffff8000635c ra : ffffffff8000635c sp : ff6000000181fbf0 > > [ 6.852562] gp : ffffffff80cff648 tp : ff60000000fdb700 t0 : 3030303030303030 > > [ 6.853852] t1 : 0000000000000030 t2 : 3030303030303030 s0 : ff6000000181fc40 > > [ 6.854984] s1 : ff60000001e6c000 a0 : 0000000000000010 a1 : ffffffff8005654c > > [ 6.856221] a2 : 00000000ffffefff a3 : 0000000000000000 a4 : 0000000000000000 > > [ 6.858114] a5 : 0000000000000000 a6 : 0000000000000008 a7 : 0000000000000038 > > [ 6.859484] s2 : ff60000001e6c068 s3 : ff6000000108abb0 s4 : 0000000000000000 > > [ 6.860751] s5 : 0000000000001000 s6 : ffffffff8089dc40 s7 : ffffffff8089dc38 > > [ 6.862029] s8 : ffffffff8089dc30 s9 : ff60000000fdbe38 s10: 000000000000005e > > [ 6.863304] s11: ffffffff80cc3510 t3 : ffffffff80d1112f t4 : ffffffff80d1112f > > [ 6.864565] t5 : ffffffff80d11130 t6 : ff6000000181fa00 > > [ 6.865561] status: 0000000000000120 badaddr: 0000000000000020 cause: 000000000000000d > > [ 6.868046] [<ffffffff8008dc94>] timens_commit+0x38/0x11a > > [ 6.869089] [<ffffffff8008dde8>] timens_on_fork+0x72/0xb4 > > [ 6.870055] [<ffffffff80190096>] begin_new_exec+0x3c6/0x9f0 > > [ 6.871231] [<ffffffff801d826c>] load_elf_binary+0x628/0x1214 > > [ 6.872304] [<ffffffff8018ee7a>] bprm_execve+0x1f2/0x4e4 > > [ 6.873243] [<ffffffff8018f90c>] do_execveat_common+0x16e/0x1ee > > [ 6.874258] [<ffffffff8018f9c8>] sys_execve+0x3c/0x48 > > [ 6.875162] [<ffffffff80003556>] ret_from_syscall+0x0/0x2 > > [ 6.877484] ---[ end trace 0000000000000000 ]--- > > > > This is because the mm->context.vdso_info is NULL in vfork case. From > > another side, mm->context.vdso_info either points to vdso info > > for RV64 or vdso info for compat, there's no need to bloat riscv's > > mm_context_t, we can handle the difference when setup the additional > > page for vdso. > > Makes sense, but I think there's a lot more diff here than we need in order
The reason of "a lot more diff" is moving the code to avoid forward declaration. If you prefer smaller fix, I can provide a simpler one w/ forware declaration. And provide a new clean up patch for next window, what do you think?
Thanks > to just fix the bug. Does something like the following still fix it? Also > at kernel.org/palmer/vdso-fix-v3 . Maybe it's a bit pedantic , but this > late in the cycle with everyone traveling I'd prefer to keep the fixes > smaller when possible. > > diff --git a/arch/riscv/include/asm/mmu.h b/arch/riscv/include/asm/mmu.h > index cedcf8ea3c76..0099dc116168 100644 > --- a/arch/riscv/include/asm/mmu.h > +++ b/arch/riscv/include/asm/mmu.h > @@ -16,7 +16,6 @@ typedef struct { > atomic_long_t id; > #endif > void *vdso; > - void *vdso_info; > #ifdef CONFIG_SMP > /* A local icache flush is needed before user execution can resume. */ > cpumask_t icache_stale_mask; > diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c > index 69b05b6c181b..58b8d73a4b1f 100644 > --- a/arch/riscv/kernel/vdso.c > +++ b/arch/riscv/kernel/vdso.c > @@ -23,8 +23,10 @@ struct vdso_data { > #endif > > extern char vdso_start[], vdso_end[]; > +static struct __vdso_info vdso_info; > #ifdef CONFIG_COMPAT > extern char compat_vdso_start[], compat_vdso_end[]; > +static struct __vdso_info compat_vdso_info; > #endif > > enum vvar_pages { > @@ -114,15 +116,18 @@ int vdso_join_timens(struct task_struct *task, struct time_namespace *ns) > { > struct mm_struct *mm = task->mm; > struct vm_area_struct *vma; > - struct __vdso_info *vdso_info = mm->context.vdso_info; > > mmap_read_lock(mm); > > for (vma = mm->mmap; vma; vma = vma->vm_next) { > unsigned long size = vma->vm_end - vma->vm_start; > > - if (vma_is_special_mapping(vma, vdso_info->dm)) > + if (vma_is_special_mapping(vma, vdso_info.dm)) > zap_page_range(vma, vma->vm_start, size); > +#ifdef CONFIG_COMPAT > + if (vma_is_special_mapping(vma, compat_vdso_info.dm)) > + zap_page_range(vma, vma->vm_start, size); > +#endif > } > > mmap_read_unlock(mm); > @@ -264,7 +269,6 @@ static int __setup_additional_pages(struct mm_struct *mm, > > vdso_base += VVAR_SIZE; > mm->context.vdso = (void *)vdso_base; > - mm->context.vdso_info = (void *)vdso_info; > > ret = > _install_special_mapping(mm, vdso_base, vdso_text_len, > > > > > Signed-off-by: Jisheng Zhang <jszhang@kernel.org> > > Fixes: 3092eb456375 ("riscv: compat: vdso: Add setup additional pages implementation") > > --- > > > > since v1: > > - add "Fixes" tag > > - fix build error when CONFIG_COMPAT is enabled. > > > > arch/riscv/include/asm/mmu.h | 1 - > > arch/riscv/kernel/vdso.c | 178 +++++++++++++++++++---------------- > > 2 files changed, 95 insertions(+), 84 deletions(-) > > > > diff --git a/arch/riscv/include/asm/mmu.h b/arch/riscv/include/asm/mmu.h > > index cedcf8ea3c76..0099dc116168 100644 > > --- a/arch/riscv/include/asm/mmu.h > > +++ b/arch/riscv/include/asm/mmu.h > > @@ -16,7 +16,6 @@ typedef struct { > > atomic_long_t id; > > #endif > > void *vdso; > > - void *vdso_info; > > #ifdef CONFIG_SMP > > /* A local icache flush is needed before user execution can resume. */ > > cpumask_t icache_stale_mask; > > diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c > > index 69b05b6c181b..8ca3b821e1b5 100644 > > --- a/arch/riscv/kernel/vdso.c > > +++ b/arch/riscv/kernel/vdso.c > > @@ -27,6 +27,11 @@ extern char vdso_start[], vdso_end[]; > > extern char compat_vdso_start[], compat_vdso_end[]; > > #endif > > > > +enum vdso_abi { > > + VDSO_ABI_RV64, > > + VDSO_ABI_RV32, > > +}; > > + > > enum vvar_pages { > > VVAR_DATA_PAGE_OFFSET, > > VVAR_TIMENS_PAGE_OFFSET, > > @@ -68,67 +73,7 @@ static int vdso_mremap(const struct vm_special_mapping *sm, > > return 0; > > } > > > > -static void __init __vdso_init(struct __vdso_info *vdso_info) > > -{ > > - unsigned int i; > > - struct page **vdso_pagelist; > > - unsigned long pfn; > > - > > - if (memcmp(vdso_info->vdso_code_start, "\177ELF", 4)) > > - panic("vDSO is not a valid ELF object!\n"); > > - > > - vdso_info->vdso_pages = ( > > - vdso_info->vdso_code_end - > > - vdso_info->vdso_code_start) >> > > - PAGE_SHIFT; > > - > > - vdso_pagelist = kcalloc(vdso_info->vdso_pages, > > - sizeof(struct page *), > > - GFP_KERNEL); > > - if (vdso_pagelist == NULL) > > - panic("vDSO kcalloc failed!\n"); > > - > > - /* Grab the vDSO code pages. */ > > - pfn = sym_to_pfn(vdso_info->vdso_code_start); > > - > > - for (i = 0; i < vdso_info->vdso_pages; i++) > > - vdso_pagelist[i] = pfn_to_page(pfn + i); > > - > > - vdso_info->cm->pages = vdso_pagelist; > > -} > > - > > #ifdef CONFIG_TIME_NS > > -struct vdso_data *arch_get_vdso_data(void *vvar_page) > > -{ > > - return (struct vdso_data *)(vvar_page); > > -} > > - > > -/* > > - * The vvar mapping contains data for a specific time namespace, so when a task > > - * changes namespace we must unmap its vvar data for the old namespace. > > - * Subsequent faults will map in data for the new namespace. > > - * > > - * For more details see timens_setup_vdso_data(). > > - */ > > -int vdso_join_timens(struct task_struct *task, struct time_namespace *ns) > > -{ > > - struct mm_struct *mm = task->mm; > > - struct vm_area_struct *vma; > > - struct __vdso_info *vdso_info = mm->context.vdso_info; > > - > > - mmap_read_lock(mm); > > - > > - for (vma = mm->mmap; vma; vma = vma->vm_next) { > > - unsigned long size = vma->vm_end - vma->vm_start; > > - > > - if (vma_is_special_mapping(vma, vdso_info->dm)) > > - zap_page_range(vma, vma->vm_start, size); > > - } > > - > > - mmap_read_unlock(mm); > > - return 0; > > -} > > - > > static struct page *find_timens_vvar_page(struct vm_area_struct *vma) > > { > > if (likely(vma->vm_mm == current->mm)) > > @@ -197,13 +142,6 @@ static struct vm_special_mapping rv_vdso_maps[] __ro_after_init = { > > }, > > }; > > > > -static struct __vdso_info vdso_info __ro_after_init = { > > - .name = "vdso", > > - .vdso_code_start = vdso_start, > > - .vdso_code_end = vdso_end, > > - .dm = &rv_vdso_maps[RV_VDSO_MAP_VVAR], > > - .cm = &rv_vdso_maps[RV_VDSO_MAP_VDSO], > > -}; > > > > #ifdef CONFIG_COMPAT > > static struct vm_special_mapping rv_compat_vdso_maps[] __ro_after_init = { > > @@ -216,21 +154,97 @@ static struct vm_special_mapping rv_compat_vdso_maps[] __ro_after_init = { > > .mremap = vdso_mremap, > > }, > > }; > > +#endif > > > > -static struct __vdso_info compat_vdso_info __ro_after_init = { > > - .name = "compat_vdso", > > - .vdso_code_start = compat_vdso_start, > > - .vdso_code_end = compat_vdso_end, > > - .dm = &rv_compat_vdso_maps[RV_VDSO_MAP_VVAR], > > - .cm = &rv_compat_vdso_maps[RV_VDSO_MAP_VDSO], > > +static struct __vdso_info vdso_info[] __ro_after_init = { > > + [VDSO_ABI_RV64] = { > > + .name = "vdso", > > + .vdso_code_start = vdso_start, > > + .vdso_code_end = vdso_end, > > + .dm = &rv_vdso_maps[RV_VDSO_MAP_VVAR], > > + .cm = &rv_vdso_maps[RV_VDSO_MAP_VDSO], > > + }, > > +#ifdef CONFIG_COMPAT > > + [VDSO_ABI_RV32] = { > > + .name = "compat_vdso", > > + .vdso_code_start = compat_vdso_start, > > + .vdso_code_end = compat_vdso_end, > > + .dm = &rv_compat_vdso_maps[RV_VDSO_MAP_VVAR], > > + .cm = &rv_compat_vdso_maps[RV_VDSO_MAP_VDSO], > > + }, > > +#endif > > }; > > + > > +static void __init __vdso_init(enum vdso_abi abi) > > +{ > > + unsigned int i; > > + struct page **vdso_pagelist; > > + unsigned long pfn; > > + > > + if (memcmp(vdso_info[abi].vdso_code_start, "\177ELF", 4)) > > + panic("vDSO is not a valid ELF object!\n"); > > + > > + vdso_info[abi].vdso_pages = ( > > + vdso_info[abi].vdso_code_end - > > + vdso_info[abi].vdso_code_start) >> > > + PAGE_SHIFT; > > + > > + vdso_pagelist = kcalloc(vdso_info[abi].vdso_pages, > > + sizeof(struct page *), > > + GFP_KERNEL); > > + if (vdso_pagelist == NULL) > > + panic("vDSO kcalloc failed!\n"); > > + > > + /* Grab the vDSO code pages. */ > > + pfn = sym_to_pfn(vdso_info[abi].vdso_code_start); > > + > > + for (i = 0; i < vdso_info[abi].vdso_pages; i++) > > + vdso_pagelist[i] = pfn_to_page(pfn + i); > > + > > + vdso_info[abi].cm->pages = vdso_pagelist; > > +} > > + > > +#ifdef CONFIG_TIME_NS > > +struct vdso_data *arch_get_vdso_data(void *vvar_page) > > +{ > > + return (struct vdso_data *)(vvar_page); > > +} > > + > > +/* > > + * The vvar mapping contains data for a specific time namespace, so when a task > > + * changes namespace we must unmap its vvar data for the old namespace. > > + * Subsequent faults will map in data for the new namespace. > > + * > > + * For more details see timens_setup_vdso_data(). > > + */ > > +int vdso_join_timens(struct task_struct *task, struct time_namespace *ns) > > +{ > > + struct mm_struct *mm = task->mm; > > + struct vm_area_struct *vma; > > + > > + mmap_read_lock(mm); > > + > > + for (vma = mm->mmap; vma; vma = vma->vm_next) { > > + unsigned long size = vma->vm_end - vma->vm_start; > > + > > + if (vma_is_special_mapping(vma, vdso_info[VDSO_ABI_RV64].dm)) > > + zap_page_range(vma, vma->vm_start, size); > > +#ifdef CONFIG_COMPAT > > + if (vma_is_special_mapping(vma, vdso_info[VDSO_ABI_RV32].dm)) > > + zap_page_range(vma, vma->vm_start, size); > > +#endif > > + } > > + > > + mmap_read_unlock(mm); > > + return 0; > > +} > > #endif > > > > static int __init vdso_init(void) > > { > > - __vdso_init(&vdso_info); > > + __vdso_init(VDSO_ABI_RV64); > > #ifdef CONFIG_COMPAT > > - __vdso_init(&compat_vdso_info); > > + __vdso_init(VDSO_ABI_RV32); > > #endif > > > > return 0; > > @@ -240,14 +254,14 @@ arch_initcall(vdso_init); > > static int __setup_additional_pages(struct mm_struct *mm, > > struct linux_binprm *bprm, > > int uses_interp, > > - struct __vdso_info *vdso_info) > > + enum vdso_abi abi) > > { > > unsigned long vdso_base, vdso_text_len, vdso_mapping_len; > > void *ret; > > > > BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES); > > > > - vdso_text_len = vdso_info->vdso_pages << PAGE_SHIFT; > > + vdso_text_len = vdso_info[abi].vdso_pages << PAGE_SHIFT; > > /* Be sure to map the data page */ > > vdso_mapping_len = vdso_text_len + VVAR_SIZE; > > > > @@ -258,18 +272,17 @@ static int __setup_additional_pages(struct mm_struct *mm, > > } > > > > ret = _install_special_mapping(mm, vdso_base, VVAR_SIZE, > > - (VM_READ | VM_MAYREAD | VM_PFNMAP), vdso_info->dm); > > + (VM_READ | VM_MAYREAD | VM_PFNMAP), vdso_info[abi].dm); > > if (IS_ERR(ret)) > > goto up_fail; > > > > vdso_base += VVAR_SIZE; > > mm->context.vdso = (void *)vdso_base; > > - mm->context.vdso_info = (void *)vdso_info; > > > > ret = > > _install_special_mapping(mm, vdso_base, vdso_text_len, > > (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC), > > - vdso_info->cm); > > + vdso_info[abi].cm); > > > > if (IS_ERR(ret)) > > goto up_fail; > > @@ -291,8 +304,7 @@ int compat_arch_setup_additional_pages(struct linux_binprm *bprm, > > if (mmap_write_lock_killable(mm)) > > return -EINTR; > > > > - ret = __setup_additional_pages(mm, bprm, uses_interp, > > - &compat_vdso_info); > > + ret = __setup_additional_pages(mm, bprm, uses_interp, VDSO_ABI_RV32); > > mmap_write_unlock(mm); > > > > return ret; > > @@ -307,7 +319,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) > > if (mmap_write_lock_killable(mm)) > > return -EINTR; > > > > - ret = __setup_additional_pages(mm, bprm, uses_interp, &vdso_info); > > + ret = __setup_additional_pages(mm, bprm, uses_interp, VDSO_ABI_RV64); > > mmap_write_unlock(mm); > > > > return ret;
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