[ Upstream commit a9e73998f9d705c94a8dca9687633adc0f24a19a ]
While validating new map we require the @start_data to be strictly less than @end_data, which is fine for regular applications (this is why this nit didn't trigger for that long). These members are set from executable loaders such as elf handers, still it is pretty valid to have a loadable data section with zero size in file, in such case the start_data is equal to end_data once kernel loader finishes.
As a result when we're trying to restore such programs the procedure fails and the kernel returns -EINVAL. From the image dump of a program:
| "mm_start_code": "0x400000", | "mm_end_code": "0x8f5fb4", | "mm_start_data": "0xf1bfb0", | "mm_end_data": "0xf1bfb0",
Thus we need to change validate_prctl_map from strictly less to less or equal operator use.
Link: http://lkml.kernel.org/r/20190408143554.GY1421@uranus.lan Fixes: f606b77f1a9e3 ("prctl: PR_SET_MM -- introduce PR_SET_MM_MAP operation") Signed-off-by: Cyrill Gorcunov gorcunov@gmail.com Cc: Andrey Vagin avagin@gmail.com Cc: Dmitry Safonov 0x7f454c46@gmail.com Cc: Pavel Emelyanov xemul@virtuozzo.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/sys.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/sys.c b/kernel/sys.c index e2446ade79ba..1855f1bf113e 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1762,7 +1762,7 @@ static int validate_prctl_map(struct prctl_mm_map *prctl_map) ((unsigned long)prctl_map->__m1 __op \ (unsigned long)prctl_map->__m2) ? 0 : -EINVAL error = __prctl_check_order(start_code, <, end_code); - error |= __prctl_check_order(start_data, <, end_data); + error |= __prctl_check_order(start_data,<=, end_data); error |= __prctl_check_order(start_brk, <=, brk); error |= __prctl_check_order(arg_start, <=, arg_end); error |= __prctl_check_order(env_start, <=, env_end);