On Tue, Aug 26, 2025 at 05:08:51AM -0700, Breno Leitao wrote: > The kexec_buf structure was previously declared without initialization > in image_load(). This led to a UBSAN warning when the structure was > expanded and uninitialized fields were accessed [1].
Just to check my understanding, is that only a problem for new fields (e.g. the 'random' field added in [1]), or do we have UBSAN warnigns for any existing fields? I assume there's no problem with existing fields today. > Zero-initializing kexec_buf at declaration ensures all fields are > cleanly set, preventing future instances of uninitialized memory being > used. > > Andrew Morton suggested that this function is only called 3x a week[2], > thus, the memset() cost is inexpressive. > > Link: > https://lore.kernel.org/all/oninomspajhxp4omtdapxnckxydbk2nzmrix7rggmpukpnzadw@c67o7njgdgm3/ > [1] > Link: > https://lore.kernel.org/all/20250825180531.94bfb86a26a43127c0a12...@linux-foundation.org/ > [2] > Suggested-by: Andrew Morton <a...@linux-foundation.org> > Signed-off-by: Breno Leitao <lei...@debian.org> This looks fine to me, but I reckon it should be added to the series which extends kexec_buf, unless there's some reason to avoid that? > --- > arch/arm64/kernel/kexec_image.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) IIUC arch/arm64/kernel/machine_kexec_file.c would need the same treatment in load_other_segments(). If other architectures need this, it'd probably make sense to clean that up treewide in one go. It looks like at least riscv and s390 need that from a quick grep: | [mark@lakrids:~/src/linux]% git grep -w 'struct kexec_buf .*;' | arch/arm64/kernel/kexec_image.c: struct kexec_buf kbuf; | arch/arm64/kernel/machine_kexec_file.c: struct kexec_buf kbuf; | arch/powerpc/include/asm/kexec.h:int arch_kexec_locate_mem_hole(struct kexec_buf *kbuf); | arch/powerpc/include/asm/kexec.h: struct kexec_buf *kbuf); | arch/riscv/kernel/elf_kexec.c: struct kexec_buf kbuf; | arch/riscv/kernel/elf_kexec.c: struct kexec_buf kbuf; | arch/riscv/kernel/elf_kexec.c: struct kexec_buf kbuf; | arch/s390/kernel/kexec_elf.c: struct kexec_buf buf; | arch/s390/kernel/kexec_image.c: struct kexec_buf buf; | arch/s390/kernel/machine_kexec_file.c: struct kexec_buf buf; | arch/s390/kernel/machine_kexec_file.c: struct kexec_buf buf; | arch/s390/kernel/machine_kexec_file.c: struct kexec_buf buf; | include/linux/kexec.h:int kexec_load_purgatory(struct kimage *image, struct kexec_buf *kbuf); | include/linux/kexec.h:extern int kexec_add_buffer(struct kexec_buf *kbuf); | include/linux/kexec.h:int kexec_locate_mem_hole(struct kexec_buf *kbuf); | kernel/kexec_file.c: struct kexec_buf *kbuf = (struct kexec_buf *)arg; Mark. > > diff --git a/arch/arm64/kernel/kexec_image.c b/arch/arm64/kernel/kexec_image.c > index 532d72ea42ee8..b70f4df15a1ae 100644 > --- a/arch/arm64/kernel/kexec_image.c > +++ b/arch/arm64/kernel/kexec_image.c > @@ -41,7 +41,7 @@ static void *image_load(struct kimage *image, > struct arm64_image_header *h; > u64 flags, value; > bool be_image, be_kernel; > - struct kexec_buf kbuf; > + struct kexec_buf kbuf = {}; > unsigned long text_offset, kernel_segment_number; > struct kexec_segment *kernel_segment; > int ret; > > --- > base-commit: 7a77c6b5ce68a71b9102760a988a4564ff6d4106 > change-id: 20250826-akpm-18a57e3a39fd > > Best regards, > -- > Breno Leitao <lei...@debian.org> > >
