From: Yongxin Liu <[email protected]>

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: ba386777a30b ("x86/elf: Add a new FPU buffer layout info to x86 core 
files")
Link: 
https://patch.msgid.link/[email protected]
Signed-off-by: Yongxin Liu <[email protected]>
---
 arch/x86/kernel/fpu/xstate.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 22abb5ee0cf2..aacb59c4a35c 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -1879,7 +1879,7 @@ static int dump_xsave_layout_desc(struct coredump_params 
*cprm)
                };
 
                if (!dump_emit(cprm, &xc, sizeof(xc)))
-                       return 0;
+                       return -1;
 
                num_records++;
        }
@@ -1917,7 +1917,7 @@ 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 */
-- 
2.46.2

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