From: Liam Howlett liam.howlett@oracle.com
[ Upstream commit f829b4b212a315b912cb23fd10aaf30534bb5ce9 ]
When the superuser flushes the entire cache, the mmap_read_lock() is not taken, but mmap_read_unlock() is called. Add the missing mmap_read_lock() call.
Fixes: cd2567b6850b1648 ("m68k: call find_vma with the mmap_sem held in sys_cacheflush()") Signed-off-by: Liam R. Howlett Liam.Howlett@Oracle.com Reviewed-by: Matthew Wilcox (Oracle) willy@infradead.org Link: https://lore.kernel.org/r/20210407200032.764445-1-Liam.Howlett@Oracle.com Signed-off-by: Geert Uytterhoeven geert@linux-m68k.org [ mmap_read_lock() open-coded using down_read() as was done prior to v5.8 ] Signed-off-by: Finn Thain fthain@linux-m68k.org --- arch/m68k/kernel/sys_m68k.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/arch/m68k/kernel/sys_m68k.c b/arch/m68k/kernel/sys_m68k.c index 6363ec83a290..38dcc1a2097d 100644 --- a/arch/m68k/kernel/sys_m68k.c +++ b/arch/m68k/kernel/sys_m68k.c @@ -388,6 +388,8 @@ sys_cacheflush (unsigned long addr, int scope, int cache, unsigned long len) ret = -EPERM; if (!capable(CAP_SYS_ADMIN)) goto out; + + down_read(¤t->mm->mmap_sem); } else { struct vm_area_struct *vma;
[ Sasha's backport helper bot ]
Hi,
The upstream commit SHA1 provided is correct: f829b4b212a315b912cb23fd10aaf30534bb5ce9
WARNING: Author mismatch between patch and upstream commit: Backport author: Finn Thainfthain@linux-m68k.org Commit author: Liam Howlettliam.howlett@oracle.com
Status in newer kernel trees: 6.12.y | Present (exact SHA1) 6.6.y | Present (exact SHA1) 6.1.y | Present (exact SHA1) 5.15.y | Present (exact SHA1) 5.10.y | Present (different SHA1: 58ee5a0de192) 5.4.y | Not found
Note: The patch differs from the upstream commit: --- 1: f829b4b212a31 ! 1: 9f4fbaa4b6d79 m68k: Add missing mmap_read_lock() to sys_cacheflush() @@ Metadata ## Commit message ## m68k: Add missing mmap_read_lock() to sys_cacheflush()
+ [ Upstream commit f829b4b212a315b912cb23fd10aaf30534bb5ce9 ] + When the superuser flushes the entire cache, the mmap_read_lock() is not taken, but mmap_read_unlock() is called. Add the missing mmap_read_lock() call. @@ Commit message Reviewed-by: Matthew Wilcox (Oracle) willy@infradead.org Link: https://lore.kernel.org/r/20210407200032.764445-1-Liam.Howlett@Oracle.com Signed-off-by: Geert Uytterhoeven geert@linux-m68k.org + [ mmap_read_lock() open-coded using down_read() as was done prior to v5.8 ] + Signed-off-by: Finn Thain fthain@linux-m68k.org
## arch/m68k/kernel/sys_m68k.c ## @@ arch/m68k/kernel/sys_m68k.c: sys_cacheflush (unsigned long addr, int scope, int cache, unsigned long len) @@ arch/m68k/kernel/sys_m68k.c: sys_cacheflush (unsigned long addr, int scope, int if (!capable(CAP_SYS_ADMIN)) goto out; + -+ mmap_read_lock(current->mm); ++ down_read(¤t->mm->mmap_sem); } else { struct vm_area_struct *vma;
---
Results of testing on various branches:
| Branch | Patch Apply | Build Test | |---------------------------|-------------|------------| | stable/linux-5.4.y | Success | Success |
linux-stable-mirror@lists.linaro.org
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Finn Thain -
Sasha Levin