I have found a race in core dumping. In binfmt_aout.c, binfmt_elf.c and
binfmt_aout32.c file->f_op->write is called without lock and so more
processes can get to VFS write function. This is the patch. I hope it
fixes the race. (but I can't reproduce it).
Mikulas
--- linux/fs/binfmt_aout.c.or Mon May 10 15:21:05 1999
+++ linux/fs/binfmt_aout.c Mon May 10 15:28:40 1999
@@ -58,8 +58,19 @@
* These are the only things you should do on a core-file: use only these
* macros to write out all the necessary info.
*/
-#define DUMP_WRITE(addr,nr) \
-while (file->f_op->write(file,(char *)(addr),(nr),&file->f_pos) != (nr)) goto close_coredump
+
+static int dump_write(struct file *file, const void *addr, int nr)
+{
+ int r;
+ down(&file->f_dentry->d_inode->i_sem);
+ r = file->f_op->write(file, addr, nr, &file->f_pos) == nr;
+ up(&file->f_dentry->d_inode->i_sem);
+ return r;
+}
+
+#define DUMP_WRITE(addr, nr) \
+ if (!dump_write(file, (void *)(addr), (nr))) \
+ goto close_coredump;
#define DUMP_SEEK(offset) \
if (file->f_op->llseek) { \
--- linux/fs/binfmt_elf.c.or Mon May 10 15:21:14 1999
+++ linux/fs/binfmt_elf.c Mon May 10 15:28:28 1999
@@ -927,7 +927,11 @@
*/
static int dump_write(struct file *file, const void *addr, int nr)
{
- return file->f_op->write(file, addr, nr, &file->f_pos) == nr;
+ int r;
+ down(&file->f_dentry->d_inode->i_sem);
+ r = file->f_op->write(file, addr, nr, &file->f_pos) == nr;
+ up(&file->f_dentry->d_inode->i_sem);
+ return r;
}
static int dump_seek(struct file *file, off_t off)
--- linux/arch/sparc64/kernel/binfmt_aout32.c.or Mon May 10 15:31:47 1999
+++ linux/arch/sparc64/kernel/binfmt_aout32.c Mon May 10 15:28:33 1999
@@ -57,8 +57,19 @@
* These are the only things you should do on a core-file: use only these
* macros to write out all the necessary info.
*/
-#define DUMP_WRITE(addr,nr) \
-while (file->f_op->write(file,(char *)(addr),(nr),&file->f_pos) != (nr)) goto close_coredump
+
+static int dump_write(struct file *file, const void *addr, int nr)
+{
+ int r;
+ down(&file->f_dentry->d_inode->i_sem);
+ r = file->f_op->write(file, addr, nr, &file->f_pos) == nr;
+ up(&file->f_dentry->d_inode->i_sem);
+ return r;
+}
+
+#define DUMP_WRITE(addr, nr) \
+ if (!dump_write(file, (void *)(addr), (nr))) \
+ goto close_coredump;
#define DUMP_SEEK(offset) \
if (file->f_op->llseek) { \
-
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