In the Linux kernel, the following vulnerability has been resolved:
ext4: update orig_path in ext4_find_extent()
In ext4_find_extent(), if the path is not big enough, we free it and set
*orig_path to NULL. But after reallocating and successfully initializing
the path, we don't update *orig_path, in which case the caller gets a
valid path but a NULL ppath, and this may cause a NULL pointer dereference
or a path memory leak. For example:
ext4_split_extent
  path = *ppath = 2000
  ext4_find_extent
    if (depth > path[0].p_maxdepth)
      kfree(path = 2000);
      *orig_path = path = NULL;
      path = kcalloc() = 3000
  ext4_split_extent_at(*ppath = NULL)
    path = *ppath;
    ex = path[depth].p_ext;
    // NULL pointer dereference!
==================================================================
BUG: kernel NULL pointer dereference, address: 0000000000000010
CPU: 6 UID: 0 PID: 576 Comm: fsstress Not tainted 6.11.0-rc2-dirty #847
RIP: 0010:ext4_split_extent_at+0x6d/0x560
Call Trace:
 <TASK>
 ext4_split_extent.isra.0+0xcb/0x1b0
 ext4_ext_convert_to_initialized+0x168/0x6c0
 ext4_ext_handle_unwritten_extents+0x325/0x4d0
 ext4_ext_map_blocks+0x520/0xdb0
 ext4_map_blocks+0x2b0/0x690
 ext4_iomap_begin+0x20e/0x2c0
[...]
==================================================================
Therefore, *orig_path is updated when the extent lookup succeeds, so that
the caller can safely use path or *ppath.
                
            Metrics
Affected Vendors & Products
References
        History
                    Mon, 03 Nov 2025 23:30:00 +0000
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Mon, 03 Nov 2025 21:30:00 +0000
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Wed, 14 May 2025 02:30:00 +0000
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        Redhat
         Redhat enterprise Linux  | 
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| CPEs | cpe:/a:redhat:enterprise_linux:9 cpe:/o:redhat:enterprise_linux:9  | 
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        Redhat
         Redhat enterprise Linux  | 
Fri, 08 Nov 2024 16:00:00 +0000
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Fri, 25 Oct 2024 15:00:00 +0000
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        Linux
         Linux linux Kernel  | 
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| Weaknesses | CWE-476 | |
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products | 
        
        Linux
         Linux linux Kernel  | 
Wed, 23 Oct 2024 01:30:00 +0000
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        threat_severity
         
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        cvssV3_1
         
 
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Tue, 22 Oct 2024 14:15:00 +0000
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        ssvc
         
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Mon, 21 Oct 2024 18:15:00 +0000
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| Description | In the Linux kernel, the following vulnerability has been resolved: ext4: update orig_path in ext4_find_extent() In ext4_find_extent(), if the path is not big enough, we free it and set *orig_path to NULL. But after reallocating and successfully initializing the path, we don't update *orig_path, in which case the caller gets a valid path but a NULL ppath, and this may cause a NULL pointer dereference or a path memory leak. For example: ext4_split_extent path = *ppath = 2000 ext4_find_extent if (depth > path[0].p_maxdepth) kfree(path = 2000); *orig_path = path = NULL; path = kcalloc() = 3000 ext4_split_extent_at(*ppath = NULL) path = *ppath; ex = path[depth].p_ext; // NULL pointer dereference! ================================================================== BUG: kernel NULL pointer dereference, address: 0000000000000010 CPU: 6 UID: 0 PID: 576 Comm: fsstress Not tainted 6.11.0-rc2-dirty #847 RIP: 0010:ext4_split_extent_at+0x6d/0x560 Call Trace: <TASK> ext4_split_extent.isra.0+0xcb/0x1b0 ext4_ext_convert_to_initialized+0x168/0x6c0 ext4_ext_handle_unwritten_extents+0x325/0x4d0 ext4_ext_map_blocks+0x520/0xdb0 ext4_map_blocks+0x2b0/0x690 ext4_iomap_begin+0x20e/0x2c0 [...] ================================================================== Therefore, *orig_path is updated when the extent lookup succeeds, so that the caller can safely use path or *ppath. | |
| Title | ext4: update orig_path in ext4_find_extent() | |
| References | 
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Status: PUBLISHED
Assigner: Linux
Published: 2024-10-21T18:01:19.478Z
Updated: 2025-11-03T22:22:46.626Z
Reserved: 2024-10-21T12:17:06.021Z
Link: CVE-2024-49881
Updated: 2025-11-03T22:22:46.626Z
Status : Modified
Published: 2024-10-21T18:15:10.560
Modified: 2025-11-03T23:16:28.273
Link: CVE-2024-49881