[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v3] Avoid crash calling PrintErrMesg from efi_multiboot2
On Mon, Aug 19, 2024 at 3:14 PM Jan Beulich <jbeulich@xxxxxxxx> wrote: > > On 19.08.2024 16:02, Frediano Ziglio wrote: > > On Mon, Aug 19, 2024 at 2:19 PM Jan Beulich <jbeulich@xxxxxxxx> wrote: > >> > >> On 19.08.2024 14:54, Frediano Ziglio wrote: > >>> Although code is compiled with -fpic option data is not position > >>> independent. This causes data pointer to become invalid if > >>> code is not relocated properly which is what happens for > >>> efi_multiboot2 which is called by multiboot entry code. > >>> > >>> Code tested adding > >>> PrintErrMesg(L"Test message", EFI_BUFFER_TOO_SMALL); > >>> in efi_multiboot2 before calling efi_arch_edd (this function > >>> can potentially call PrintErrMesg). > >>> > >>> Before the patch (XenServer installation on Qemu, xen replaced > >>> with vanilla xen.gz): > >>> Booting `XenServer (Serial)'Booting `XenServer (Serial)' > >>> Test message: !!!! X64 Exception Type - 0E(#PF - Page-Fault) CPU Apic > >>> ID - 00000000 !!!! > >>> ExceptionData - 0000000000000000 I:0 R:0 U:0 W:0 P:0 PK:0 SS:0 SGX:0 > >>> RIP - 000000007DC29E46, CS - 0000000000000038, RFLAGS - > >>> 0000000000210246 > >>> RAX - 0000000000000000, RCX - 0000000000000050, RDX - 0000000000000000 > >>> RBX - 000000007DAB4558, RSP - 000000007EFA1200, RBP - 0000000000000000 > >>> RSI - FFFF82D040467A88, RDI - 0000000000000000 > >>> R8 - 000000007EFA1238, R9 - 000000007EFA1230, R10 - 0000000000000000 > >>> R11 - 000000007CF42665, R12 - FFFF82D040467A88, R13 - 000000007EFA1228 > >>> R14 - 000000007EFA1225, R15 - 000000007DAB45A8 > >>> DS - 0000000000000030, ES - 0000000000000030, FS - 0000000000000030 > >>> GS - 0000000000000030, SS - 0000000000000030 > >>> CR0 - 0000000080010033, CR2 - FFFF82D040467A88, CR3 - 000000007EC01000 > >>> CR4 - 0000000000000668, CR8 - 0000000000000000 > >>> DR0 - 0000000000000000, DR1 - 0000000000000000, DR2 - 0000000000000000 > >>> DR3 - 0000000000000000, DR6 - 00000000FFFF0FF0, DR7 - 0000000000000400 > >>> GDTR - 000000007E9E2000 0000000000000047, LDTR - 0000000000000000 > >>> IDTR - 000000007E4E5018 0000000000000FFF, TR - 0000000000000000 > >>> FXSAVE_STATE - 000000007EFA0E60 > >>> !!!! Find image based on IP(0x7DC29E46) (No PDB) > >>> (ImageBase=000000007DC28000, EntryPoint=000000007DC2B917) !!!! > >>> > >>> After the patch: > >>> Booting `XenServer (Serial)'Booting `XenServer (Serial)' > >>> Test message: Buffer too small > >>> BdsDxe: loading Boot0000 "UiApp" from > >>> Fv(7CB8BDC9-F8EB-4F34-AAEA-3EE4AF6516A1)/FvFile(462CAA21-7614-4503-836E-8AB6F4662331) > >>> BdsDxe: starting Boot0000 "UiApp" from > >>> Fv(7CB8BDC9-F8EB-4F34-AAEA-3EE4AF6516A1)/FvFile(462CAA21-7614-4503-836E-8AB6F4662331) > >>> > >>> Fixes: 00d5d5ce23e6 ("work around Clang generating .data.rel.ro section > >>> for init-only files") > > > > ^^^^ here ?? > > Did you not see ... > > >>> Signed-off-by: Frediano Ziglio <frediano.ziglio@xxxxxxxxx> > >>> --- > >>> xen/common/efi/boot.c | 46 ++++++++++++++++++++++++++++++------------- > >>> 1 file changed, 32 insertions(+), 14 deletions(-) > >>> --- > >>> Changes since v1: > >>> - added "Fixes:" tag; > >>> - fixed cast style change. > >>> > >>> Changes since v2: > >>> - wrap long line. > >> > >> And what about the Fixes: tag? > > ... my respective v2 comment then? There I said: > > "I don't think this is right. While this is where the array was introduced, > it was correct at that time afaict. It went wrong when MB2 support was added > about a year later. 9180f5365524 ("x86: add multiboot2 protocol support for > EFI platforms") may be reasonable to blame, albeit I'm not sure that was the > final one, after which MB2 support was considered complete." > > Jan Yes, missed, updated Frediano
|
![]() |
Lists.xenproject.org is hosted with RackSpace, monitoring our |