6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kees Cook <kees@xxxxxxxxxx>
[ Upstream commit 39ec9eaaa165d297d008d1fa385748430bd18e4d ]
The sorting of VMAs by size in commit 7d442a33bfe8 ("binfmt_elf: Dump
smaller VMAs first in ELF cores") breaks elfutils[1]. Instead, sort
based on the setting of the new sysctl, core_sort_vma, which defaults
to 0, no sorting.
Reported-by: Michael Stapelberg <michael@xxxxxxxxxxxxx>
Closes: https://lore.kernel.org/all/20250218085407.61126-1-michael@xxxxxxxxxxxxx/ [1]
Fixes: 7d442a33bfe8 ("binfmt_elf: Dump smaller VMAs first in ELF cores")
Signed-off-by: Kees Cook <kees@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
Documentation/admin-guide/sysctl/kernel.rst | 11 +++++++++++
fs/coredump.c | 15 +++++++++++++--
2 files changed, 24 insertions(+), 2 deletions(-)
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index f8bc1630eba05..fa21cdd610b21 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -212,6 +212,17 @@ pid>/``).
This value defaults to 0.
+core_sort_vma
+=============
+
+The default coredump writes VMAs in address order. By setting
+``core_sort_vma`` to 1, VMAs will be written from smallest size
+to largest size. This is known to break at least elfutils, but
+can be handy when dealing with very large (and truncated)
+coredumps where the more useful debugging details are included
+in the smaller VMAs.
+
+
core_uses_pid
=============
diff --git a/fs/coredump.c b/fs/coredump.c
index 45737b43dda5c..2b8c36c9660c5 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -63,6 +63,7 @@ static void free_vma_snapshot(struct coredump_params *cprm);
static int core_uses_pid;
static unsigned int core_pipe_limit;
+static unsigned int core_sort_vma;
static char core_pattern[CORENAME_MAX_SIZE] = "core";
static int core_name_size = CORENAME_MAX_SIZE;
unsigned int core_file_note_size_limit = CORE_FILE_NOTE_SIZE_DEFAULT;
@@ -1025,6 +1026,15 @@ static struct ctl_table coredump_sysctls[] = {
.extra1 = (unsigned int *)&core_file_note_size_min,
.extra2 = (unsigned int *)&core_file_note_size_max,
},
+ {
+ .procname = "core_sort_vma",
+ .data = &core_sort_vma,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_douintvec_minmax,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_ONE,
+ },
};
static int __init init_fs_coredump_sysctls(void)
@@ -1255,8 +1265,9 @@ static bool dump_vma_snapshot(struct coredump_params *cprm)
cprm->vma_data_size += m->dump_size;
}
- sort(cprm->vma_meta, cprm->vma_count, sizeof(*cprm->vma_meta),
- cmp_vma_size, NULL);
+ if (core_sort_vma)
+ sort(cprm->vma_meta, cprm->vma_count, sizeof(*cprm->vma_meta),
+ cmp_vma_size, NULL);
return true;
}
--
2.39.5
