Messages in this thread | | | Subject | Re: [PATCH] x86/boot/compressed/64: Fix 'may be used uninitialized' issue | From | Zhenzhong Duan <> | Date | Mon, 2 Sep 2019 17:40:28 +0800 |
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On 2019/9/2 17:35, Borislav Petkov wrote: > On Mon, Sep 02, 2019 at 05:30:24PM +0800, Zhenzhong Duan wrote: >> Builds kernel with "make bzImage EXTRA_CFLAGS=-Wall", gcc complains: >> >> arch/x86/boot/compressed/pgtable_64.c: In function 'paging_prepare': >> arch/x86/boot/compressed/pgtable_64.c:92:7: warning: 'new' may be used uninitialized in this function [-Wmaybe-uninitialized] >> new = round_down(new, PAGE_SIZE); >> >> In theory a random value of variable new may pass all the check and be >> assigned to bios_start, fixing it by assigning it an initial value. >> >> Fixes: 0a46fff2f910 ("x86/boot/compressed/64: Fix boot on machines with broken E820 table") >> Signed-off-by: Zhenzhong Duan<zhenzhong.duan@oracle.com> >> Cc: Kirill A. Shutemov<kirill@shutemov.name> >> Cc: Thomas Gleixner<tglx@linutronix.de> >> Cc: Ingo Molnar<mingo@redhat.com> >> Cc: Borislav Petkov<bp@alien8.de> >> Cc: "H. Peter Anvin"<hpa@zytor.com> >> Cc: x86-ml<x86@kernel.org> >> --- >> arch/x86/boot/compressed/pgtable_64.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/x86/boot/compressed/pgtable_64.c b/arch/x86/boot/compressed/pgtable_64.c >> index 2faddeb..c886269 100644 >> --- a/arch/x86/boot/compressed/pgtable_64.c >> +++ b/arch/x86/boot/compressed/pgtable_64.c >> @@ -72,7 +72,7 @@ static unsigned long find_trampoline_placement(void) >> >> /* Find the first usable memory region under bios_start. */ >> for (i = boot_params->e820_entries - 1; i >= 0; i--) { >> - unsigned long new; >> + unsigned long new = bios_start; >> >> entry = &boot_params->e820_table[i]; >> >> -- > https://git.kernel.org/tip/c96e8483cb2da6695c8b8d0896fe7ae272a07b54 > > In the future, use tip/master when preparing fixes because it has the > latest state of the x86 tree and you won't have to duplicate effort, > like in this case.
Ok, I see. Thanks for your suggestion.
Zhenzhong
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