6.12-stable review patch. If anyone has any objections, please let me know.
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From: Kees Cook kees@kernel.org
[ 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@stapelberg.ch Closes: https://lore.kernel.org/all/20250218085407.61126-1-michael@stapelberg.de/ [1] Fixes: 7d442a33bfe8 ("binfmt_elf: Dump smaller VMAs first in ELF cores") Signed-off-by: Kees Cook kees@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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; }