Re: [PATCH 2/2] ext4: Fix zalloc()

[Heinrich Schuchardt]

On 02.07.24 21:42, Richard Weinberger wrote:

The zalloc() function suffers from two problems.
1. If memalign() fails it will return NULL and memset() will use a NULL pointer.
2. memalign() itself seems to crash when more than 2^32 bytes are requested.

So, check the return value of memalign() and allocate only of size is less than
CONFIG_SYS_MALLOC_LEN.

Signed-off-by: Richard Weinberger <rich...@nod.at>
---
FWIW, I didn't investigate further why memalign() fails for large sizes.
Maybe this is an issue on it's own.

Thanks,
//richard
---
  fs/ext4/ext4_common.h | 10 ++++++++--
  1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/ext4_common.h b/fs/ext4/ext4_common.h
index 84500e990a..0d1f72ae01 100644
--- a/fs/ext4/ext4_common.h
+++ b/fs/ext4/ext4_common.h
@@ -43,8 +43,14 @@

  static inline void *zalloc(size_t size)
  {
-       void *p = memalign(ARCH_DMA_MINALIGN, size);
-       memset(p, 0, size);
+       void *p = NULL;
+
+       if (size < CONFIG_SYS_MALLOC_LEN)
+               p = memalign(ARCH_DMA_MINALIGN, size);

Memalign() is called in many code locations.

If memalign() has a bug, it needs to be fixed in memalign. We should not
try to work around it in all callers.

Best regards

Heinrich

+
+       if (p)
+               memset(p, 0, size);
+
        return p;
  }