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Subject[PATCH] coredump: prevent double-free on an error path in core dumper
Date
In !CORE_DUMP_USE_REGSET case, if elf_note_info_init fails to allocate memory
for info->fields, it frees already allocated stuff and returns
error to its caller, fill_note_info. Which in turn returns
error to its caller, elf_core_dump. Which jumps to cleanup
label and calls free_note_info, which will happily try to
free all info->fields again. BOOM.

This is the fix.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
---
fs/binfmt_elf.c | 19 ++++---------------
1 files changed, 4 insertions(+), 15 deletions(-)

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 760d7f5..1b4efbc 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1695,30 +1695,19 @@ static int elf_note_info_init(struct elf_note_info *info)
return 0;
info->psinfo = kmalloc(sizeof(*info->psinfo), GFP_KERNEL);
if (!info->psinfo)
- goto notes_free;
+ return 0;
info->prstatus = kmalloc(sizeof(*info->prstatus), GFP_KERNEL);
if (!info->prstatus)
- goto psinfo_free;
+ return 0;
info->fpu = kmalloc(sizeof(*info->fpu), GFP_KERNEL);
if (!info->fpu)
- goto prstatus_free;
+ return 0;
#ifdef ELF_CORE_COPY_XFPREGS
info->xfpu = kmalloc(sizeof(*info->xfpu), GFP_KERNEL);
if (!info->xfpu)
- goto fpu_free;
+ return 0;
#endif
return 1;
-#ifdef ELF_CORE_COPY_XFPREGS
- fpu_free:
- kfree(info->fpu);
-#endif
- prstatus_free:
- kfree(info->prstatus);
- psinfo_free:
- kfree(info->psinfo);
- notes_free:
- kfree(info->notes);
- return 0;
}

static int fill_note_info(struct elfhdr *elf, int phdrs,
--
1.7.7.6


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