From: Michal Hocko <mhocko@xxxxxxxx>
Subject: mm, aout: handle vm_brk failures
vm_brk is allowed to fail but load_aout_binary simply ignores the error
and happily continues. I haven't noticed any problem from that in real
life but later patches will make the failure more likely because vm_brk
will become killable (resp. mmap_sem for write waiting will become
killable) so we should be more careful now.
The error handling should be quite straightforward because there are calls
to vm_mmap which check the error properly already. The only notable
exception is set_brk which is called after beyond_if label. But nothing
indicates that we cannot move it above set_binfmt as the two do not depend
on each other and fail before we do set_binfmt and alter reference
counting.
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/ia32/ia32_aout.c | 22 +++++++++++++++-------
fs/binfmt_aout.c | 11 ++++++++---
2 files changed, 23 insertions(+), 10 deletions(-)
diff -puN arch/x86/ia32/ia32_aout.c~mm-aout-handle-vm_brk-failures arch/x86/ia32/ia32_aout.c
--- a/arch/x86/ia32/ia32_aout.c~mm-aout-handle-vm_brk-failures
+++ a/arch/x86/ia32/ia32_aout.c
@@ -116,13 +116,13 @@ static struct linux_binfmt aout_format =
.min_coredump = PAGE_SIZE
};
-static void set_brk(unsigned long start, unsigned long end)
+static unsigned long set_brk(unsigned long start, unsigned long end)
{
start = PAGE_ALIGN(start);
end = PAGE_ALIGN(end);
if (end <= start)
- return;
- vm_brk(start, end - start);
+ return start;
+ return vm_brk(start, end - start);
}
#ifdef CONFIG_COREDUMP
@@ -349,7 +349,10 @@ static int load_aout_binary(struct linux
#endif
if (!bprm->file->f_op->mmap || (fd_offset & ~PAGE_MASK) != 0) {
- vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
+ error = vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
+ if (IS_ERR_VALUE(error))
+ return error;
+
read_code(bprm->file, N_TXTADDR(ex), fd_offset,
ex.a_text+ex.a_data);
goto beyond_if;
@@ -372,10 +375,13 @@ static int load_aout_binary(struct linux
if (error != N_DATADDR(ex))
return error;
}
+
beyond_if:
- set_binfmt(&aout_format);
+ error = set_brk(current->mm->start_brk, current->mm->brk);
+ if (IS_ERR_VALUE(error))
+ return error;
- set_brk(current->mm->start_brk, current->mm->brk);
+ set_binfmt(&aout_format);
current->mm->start_stack =
(unsigned long)create_aout_tables((char __user *)bprm->p, bprm);
@@ -434,7 +440,9 @@ static int load_aout_library(struct file
error_time = jiffies;
}
#endif
- vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
+ retval = vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
+ if (IS_ERR_VALUE(retval))
+ goto out;
read_code(file, start_addr, N_TXTOFF(ex),
ex.a_text + ex.a_data);
diff -puN fs/binfmt_aout.c~mm-aout-handle-vm_brk-failures fs/binfmt_aout.c
--- a/fs/binfmt_aout.c~mm-aout-handle-vm_brk-failures
+++ a/fs/binfmt_aout.c
@@ -297,7 +297,10 @@ static int load_aout_binary(struct linux
}
if (!bprm->file->f_op->mmap||((fd_offset & ~PAGE_MASK) != 0)) {
- vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
+ error = vm_brk(N_TXTADDR(ex), ex.a_text+ex.a_data);
+ if (IS_ERR_VALUE(error))
+ return error;
+
read_code(bprm->file, N_TXTADDR(ex), fd_offset,
ex.a_text + ex.a_data);
goto beyond_if;
@@ -378,8 +381,10 @@ static int load_aout_library(struct file
"N_TXTOFF is not page aligned. Please convert library: %pD\n",
file);
}
- vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
-
+ retval = vm_brk(start_addr, ex.a_text + ex.a_data + ex.a_bss);
+ if (IS_ERR_VALUE(retval))
+ goto out;
+
read_code(file, start_addr, N_TXTOFF(ex),
ex.a_text + ex.a_data);
retval = 0;
_
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
