Messages in this thread | | | Date | Mon, 16 Dec 2019 10:45:56 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH 3/5] init: use do_mount() instead of ksys_mount() |
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On Thu, Dec 12, 2019 at 07:14:20PM +0100, Dominik Brodowski wrote: > diff --git a/init/do_mounts.c b/init/do_mounts.c > index 43f6d098c880..f55cbd9cb818 100644 > --- a/init/do_mounts.c > +++ b/init/do_mounts.c > @@ -387,12 +387,25 @@ static void __init get_fs_names(char *page) > *s = '\0'; > } > > -static int __init do_mount_root(char *name, char *fs, int flags, void *data) > +static int __init do_mount_root(const char *name, const char *fs, > + const int flags, const void *data) > { > struct super_block *s; > - int err = ksys_mount(name, "/root", fs, flags, data); > - if (err) > - return err; > + char *data_page; > + struct page *p; > + int ret; > + > + /* do_mount() requires a full page as fifth argument */ > + p = alloc_page(GFP_KERNEL); > + if (!p) > + return -ENOMEM; > + > + data_page = page_address(p); ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
That doesn't work in my guest as it gives a funny address:
[ 3.155314] mount_block_root: entry [ 3.155868] mount_block_root: fs_name: [ext3] [ 3.156512] do_mount_root: will copy data page: 0x00000000adf0ddb8
leading to the splat below.
Reverting the patch fixes the boot.
Thx.
[ 3.575074] BUG: kernel NULL pointer dereference, address: 0000000000000000 [ 3.576858] #PF: supervisor read access in kernel mode [ 3.578274] #PF: error_code(0x0000) - not-present page [ 3.579003] PGD 0 P4D 0 [ 3.579003] Oops: 0000 [#1] PREEMPT SMP [ 3.579003] CPU: 8 PID: 1 Comm: swapper/0 Not tainted 5.5.0-rc1+ #17 [ 3.579003] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.1-1 04/01/2014 [ 3.579003] RIP: 0010:strncpy+0xf/0x30 [ 3.579003] Code: 0f b6 0c 16 88 0c 10 48 ff c2 84 c9 75 f2 f3 c3 66 66 2e 0f 1f 84 00 00 00 00 00 48 85 d2 48 89 f8 74 1b 4c 8d 04 17 48 89 fa <0f> b6 0e 80 f9 01 88 0a 48 83 de ff 48 ff c2 4c 39 c2 75 ec f3 c3 [ 3.579003] RSP: 0018:ffffc90000013eb8 EFLAGS: 00010206 [ 3.579003] RAX: ffff88807b780000 RBX: 0000000000008001 RCX: 0000000000000000 [ 3.579003] RDX: ffff88807b780000 RSI: 0000000000000000 RDI: ffff88807b780000 [ 3.579003] RBP: ffff88807b781000 R08: ffff88807b780fff R09: 00000000000770f4 [ 3.579003] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88807b781000 [ 3.579003] R13: 0000000000000000 R14: 0000000000000000 R15: ffffea0001ede000 [ 3.579003] FS: 0000000000000000(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000 [ 3.579003] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 3.579003] CR2: 0000000000000000 CR3: 0000000002009000 CR4: 00000000003406e0 [ 3.579003] Call Trace: [ 3.579003] mount_block_root+0x14f/0x312 [ 3.579003] prepare_namespace+0x136/0x165 [ 3.579003] ? rest_init+0xb9/0xb9 [ 3.579003] kernel_init+0xa/0xf7 [ 3.579003] ret_from_fork+0x22/0x40 [ 3.579003] Modules linked in: [ 3.579003] CR2: 0000000000000000 [ 3.579003] ---[ end trace 2884b7e501f1daa6 ]--- [ 3.579003] RIP: 0010:strncpy+0xf/0x30 [ 3.579003] Code: 0f b6 0c 16 88 0c 10 48 ff c2 84 c9 75 f2 f3 c3 66 66 2e 0f 1f 84 00 00 00 00 00 48 85 d2 48 89 f8 74 1b 4c 8d 04 17 48 89 fa <0f> b6 0e 80 f9 01 88 0a 48 83 de ff 48 ff c2 4c 39 c2 75 ec f3 c3 [ 3.579003] RSP: 0018:ffffc90000013eb8 EFLAGS: 00010206 [ 3.579003] RAX: ffff88807b780000 RBX: 0000000000008001 RCX: 0000000000000000 [ 3.579003] RDX: ffff88807b780000 RSI: 0000000000000000 RDI: ffff88807b780000 [ 3.579003] RBP: ffff88807b781000 R08: ffff88807b780fff R09: 00000000000770f4 [ 3.579003] R10: 0000000000000000 R11: 0000000000000000 R12: ffff88807b781000 [ 3.579003] R13: 0000000000000000 R14: 0000000000000000 R15: ffffea0001ede000 [ 3.579003] FS: 0000000000000000(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000 [ 3.579003] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 3.579003] CR2: 0000000000000000 CR3: 0000000002009000 CR4: 00000000003406e0 [ 3.611795] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009 [ 3.612923] Kernel Offset: disabled [ 3.613505] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009 ]---
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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