[PATCH 3.16 056/192] MIPS: module: Ensure we always clean up r_mips_hi16_list

Ben Hutchings
2017-10-09T13:19:10Z

From: Paul Burton <paul.burton@imgtec.com>

commit 351b0940d473146923711bc943fc881354a4c1f3 upstream.

If we hit an error whilst processing a reloc then we would return early
from apply_relocate & potentially not free entries in r_mips_hi16_list,
thereby leaking memory. Fix this by ensuring that we always run the code
to free r_mipps_hi16_list when errors occur.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Fixes: 861667dc82f5 ("MIPS: Fix race condition in module relocation code.")
Fixes: 04211a574641 ("MIPS: Bail on unsupported module relocs")
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/15831/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
arch/mips/kernel/module.c | 28 ++++++++++++++++------------
1 file changed, 16 insertions(+), 12 deletions(-)

--- a/arch/mips/kernel/module.c
+++ b/arch/mips/kernel/module.c
@@ -202,7 +202,7 @@ int apply_relocate(Elf_Shdr *sechdrs, co
u32 *location;
unsigned int i, type;
Elf_Addr v;
- int res;
+ int err = 0;

pr_debug("Applying relocate section %u to %u\n", relsec,
sechdrs[relsec].sh_info);
@@ -221,7 +221,8 @@ int apply_relocate(Elf_Shdr *sechdrs, co
continue;
printk(KERN_WARNING "%s: Unknown symbol %s\n",
me->name, strtab + sym->st_name);
- return -ENOENT;
+ err = -ENOENT;
+ goto out;
}

type = ELF_MIPS_R_TYPE(rel[i]);
@@ -234,29 +235,32 @@ int apply_relocate(Elf_Shdr *sechdrs, co
if (!handler) {
pr_err("%s: Unknown relocation type %u\n",
me->name, type);
- return -EINVAL;
+ err = -EINVAL;
+ goto out;
}

v = sym->st_value;
- res = handler(me, location, v);
- if (res)
- return res;
+ err = handler(me, location, v);
+ if (err)
+ goto out;
}

+out:
/*
- * Normally the hi16 list should be deallocated at this point. A
+ * Normally the hi16 list should be deallocated at this point. A
* malformed binary however could contain a series of R_MIPS_HI16
- * relocations not followed by a R_MIPS_LO16 relocation. In that
- * case, free up the list and return an error.
+ * relocations not followed by a R_MIPS_LO16 relocation, or if we hit
+ * an error processing a reloc we might have gotten here before
+ * reaching the R_MIPS_LO16. In either case, free up the list and
+ * return an error.
*/
if (me->arch.r_mips_hi16_list) {
free_relocation_chain(me->arch.r_mips_hi16_list);
me->arch.r_mips_hi16_list = NULL;
-
- return -ENOEXEC;
+ err = err ?: -ENOEXEC;
}

- return 0;
+ return err;
}

/* Given an address, look for it in the module exception tables. */