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Subject[PATCH -mm 1/3] ELF, coredump: allocate core ELF header on stack
Comment says ELF header is "too large to be on stack".
64 bytes on 64-bit is not large by any means.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---

fs/binfmt_elf.c | 16 +++++-----------
1 file changed, 5 insertions(+), 11 deletions(-)

--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -2186,7 +2186,7 @@ static int elf_core_dump(struct coredump_params *cprm)
int segs, i;
size_t vma_data_size = 0;
struct vm_area_struct *vma, *gate_vma;
- struct elfhdr *elf = NULL;
+ struct elfhdr elf;
loff_t offset = 0, dataoff;
struct elf_note_info info = { };
struct elf_phdr *phdr4note = NULL;
@@ -2207,10 +2207,6 @@ static int elf_core_dump(struct coredump_params *cprm)
* exists while dumping the mm->vm_next areas to the core file.
*/

- /* alloc memory for large data structures: too large to be on stack */
- elf = kmalloc(sizeof(*elf), GFP_KERNEL);
- if (!elf)
- goto out;
/*
* The number of segs are recored into ELF header as 16bit value.
* Please check DEFAULT_MAX_MAP_COUNT definition when you modify here.
@@ -2234,7 +2230,7 @@ static int elf_core_dump(struct coredump_params *cprm)
* Collect all the non-memory information about the process for the
* notes. This also sets up the file header.
*/
- if (!fill_note_info(elf, e_phnum, &info, cprm->siginfo, cprm->regs))
+ if (!fill_note_info(&elf, e_phnum, &info, cprm->siginfo, cprm->regs))
goto cleanup;

has_dumped = 1;
@@ -2242,7 +2238,7 @@ static int elf_core_dump(struct coredump_params *cprm)
fs = get_fs();
set_fs(KERNEL_DS);

- offset += sizeof(*elf); /* Elf header */
+ offset += sizeof(elf); /* Elf header */
offset += segs * sizeof(struct elf_phdr); /* Program headers */

/* Write notes phdr entry */
@@ -2285,12 +2281,12 @@ static int elf_core_dump(struct coredump_params *cprm)
shdr4extnum = kmalloc(sizeof(*shdr4extnum), GFP_KERNEL);
if (!shdr4extnum)
goto end_coredump;
- fill_extnum_info(elf, shdr4extnum, e_shoff, segs);
+ fill_extnum_info(&elf, shdr4extnum, e_shoff, segs);
}

offset = dataoff;

- if (!dump_emit(cprm, elf, sizeof(*elf)))
+ if (!dump_emit(cprm, &elf, sizeof(elf)))
goto end_coredump;

if (!dump_emit(cprm, phdr4note, sizeof(*phdr4note)))
@@ -2374,8 +2370,6 @@ static int elf_core_dump(struct coredump_params *cprm)
kfree(shdr4extnum);
kvfree(vma_filesz);
kfree(phdr4note);
- kfree(elf);
-out:
return has_dumped;
}

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