From: Michal Hocko <[email protected]> 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. Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Alexander Viro <[email protected]> Signed-off-by: Michal Hocko <[email protected]> --- arch/x86/ia32/ia32_aout.c | 22 +++++++++++++++------- fs/binfmt_aout.c | 9 +++++++-- 2 files changed, 22 insertions(+), 9 deletions(-) diff --git a/arch/x86/ia32/ia32_aout.c b/arch/x86/ia32/ia32_aout.c index ae6aad1d24f7..f5e737ff0022 100644 --- a/arch/x86/ia32/ia32_aout.c +++ b/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_binprm *bprm) #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_binprm *bprm) 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 *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 --git a/fs/binfmt_aout.c b/fs/binfmt_aout.c index 4c556680fa74..5fb075f05706 100644 --- a/fs/binfmt_aout.c +++ b/fs/binfmt_aout.c @@ -297,7 +297,10 @@ static int load_aout_binary(struct linux_binprm * bprm) } 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; @@ -378,7 +381,9 @@ static int load_aout_library(struct file *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); -- 2.7.0
