Commit c8161e53 authored by Yongxin Liu's avatar Yongxin Liu Committed by Ingo Molnar
Browse files

x86/fpu: Fix FPU state core dump truncation on CPUs with no extended xfeatures 



Zero can be a valid value of num_records. For example, on Intel Atom x6425RE,
only x87 and SSE are supported (features 0, 1), and fpu_user_cfg.max_features
is 3. The for_each_extended_xfeature() loop only iterates feature 2, which is
not enabled, so num_records = 0. This is valid and should not cause core dump
failure.

The issue is that dump_xsave_layout_desc() returns 0 for both genuine errors
(dump_emit() failure) and valid cases (no extended features). Use negative
return values for errors and only abort on genuine failures.

Fixes: ba386777 ("x86/elf: Add a new FPU buffer layout info to x86 core files")
Signed-off-by: default avatarYongxin Liu <yongxin.liu@windriver.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Link: https://patch.msgid.link/20251210000219.4094353-2-yongxin.liu@windriver.com
parent 5288176a

arch/x86/kernel/fpu/xstate.c

+2 −2
Original line number Diff line number Diff line
@@ -1946,7 +1946,7 @@ static int dump_xsave_layout_desc(struct coredump_params *cprm) 
		};



		if (!dump_emit(cprm, &xc, sizeof(xc)))

			return 0;

			return -1;



		num_records++;

	}
@@ -1984,7 +1984,7 @@ int elf_coredump_extra_notes_write(struct coredump_params *cprm) 
		return 1;



	num_records = dump_xsave_layout_desc(cprm);

	if (!num_records)

	if (num_records < 0)

		return 1;



	/* Total size should be equal to the number of records */