From: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Subject: coredump: fix spam with zero VMA process
Nobody ever tried to self destruct by unmapping whole address space at once:
munmap((void *)0, (1ULL << 47) - 4096);
Doing this produces 2 warnings for zero-length vmalloc allocations:
a.out[1353]: segfault at 7f80bcc4b757 ip 00007f80bcc4b757 sp 00007fff683939b8 error 14
a.out: vmalloc: allocation failure: 0 bytes, mode:0xcc0(GFP_KERNEL), nodemask=(null)
...
a.out: vmalloc: allocation failure: 0 bytes, mode:0xcc0(GFP_KERNEL), nodemask=(null)
...
Fix is to switch to kvmalloc().
Steps to reproduce:
// vsyscall=none
#include <sys/mman.h>
#include <sys/resource.h>
int main(void)
{
setrlimit(RLIMIT_CORE, &(struct rlimit){RLIM_INFINITY, RLIM_INFINITY});
munmap((void *)0, (1ULL << 47) - 4096);
return 0;
}
Link: http://lkml.kernel.org/r/20180410180353.GA2515@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/binfmt_elf.c | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
diff -puN fs/binfmt_elf.c~coredump-fix-spam-with-zero-vma-process fs/binfmt_elf.c
--- a/fs/binfmt_elf.c~coredump-fix-spam-with-zero-vma-process
+++ a/fs/binfmt_elf.c
@@ -1621,8 +1621,8 @@ static int fill_files_note(struct memelf
if (size >= MAX_FILE_NOTE_SIZE) /* paranoia check */
return -EINVAL;
size = round_up(size, PAGE_SIZE);
- data = vmalloc(size);
- if (!data)
+ data = kvmalloc(size, GFP_KERNEL);
+ if (ZERO_OR_NULL_PTR(data))
return -ENOMEM;
start_end_ofs = data + 2;
@@ -1639,7 +1639,7 @@ static int fill_files_note(struct memelf
filename = file_path(file, name_curpos, remaining);
if (IS_ERR(filename)) {
if (PTR_ERR(filename) == -ENAMETOOLONG) {
- vfree(data);
+ kvfree(data);
size = size * 5 / 4;
goto alloc;
}
@@ -1932,7 +1932,7 @@ static void free_note_info(struct elf_no
kfree(t);
}
kfree(info->psinfo.data);
- vfree(info->files.data);
+ kvfree(info->files.data);
}
#else
@@ -2148,7 +2148,7 @@ static void free_note_info(struct elf_no
/* Free data possibly allocated by fill_files_note(): */
if (info->notes_files)
- vfree(info->notes_files->data);
+ kvfree(info->notes_files->data);
kfree(info->prstatus);
kfree(info->psinfo);
@@ -2294,8 +2294,9 @@ static int elf_core_dump(struct coredump
if (segs - 1 > ULONG_MAX / sizeof(*vma_filesz))
goto end_coredump;
- vma_filesz = vmalloc(array_size(sizeof(*vma_filesz), (segs - 1)));
- if (!vma_filesz)
+ vma_filesz = kvmalloc(array_size(sizeof(*vma_filesz), (segs - 1)),
+ GFP_KERNEL);
+ if (ZERO_OR_NULL_PTR(vma_filesz))
goto end_coredump;
for (i = 0, vma = first_vma(current, gate_vma); vma != NULL;
@@ -2402,7 +2403,7 @@ end_coredump:
cleanup:
free_note_info(&info);
kfree(shdr4extnum);
- vfree(vma_filesz);
+ kvfree(vma_filesz);
kfree(phdr4note);
kfree(elf);
out:
_
--
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