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lib/strn*,uaccess: Use masked_user_{read/write}_access_begin when required 

Properly use masked_user_read_access_begin() and
masked_user_write_access_begin() instead of masked_user_access_begin() in
order to match user_read_access_end() and user_write_access_end().  This is
important for architectures like PowerPC that enable separately user reads
and user writes.

That means masked_user_read_access_begin() is used when user memory is
exclusively read during the window and masked_user_write_access_begin()
is used when user memory is exclusively writen during the window.
masked_user_access_begin() remains and is used when both reads and
writes are performed during the open window. Each of them is expected
to be terminated by the matching user_read_access_end(),
user_write_access_end() and user_access_end().

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://patch.msgid.link/cb5e4b0fa49ea9c740570949d5e3544423389757.1763396724.git.christophe.leroy@csgroup.eu
This commit is contained in:
Christophe Leroy 2025-11-17 17:43:44 +01:00 committed by Thomas Gleixner
parent 1c204914bc
commit 4322c8f81c
2 changed files with 2 additions and 2 deletions
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2
lib/strncpy_from_user.c
View File

@ -126,7 +126,7 @@ long strncpy_from_user(char *dst, const char __user *src, long count)
if (can_do_masked_user_access()) {
long retval;
src = masked_user_access_begin(src);
src = masked_user_read_access_begin(src);
retval = do_strncpy_from_user(dst, src, count, count);
user_read_access_end();
return retval;

2
lib/strnlen_user.c
View File

@ -99,7 +99,7 @@ long strnlen_user(const char __user *str, long count)
if (can_do_masked_user_access()) {
long retval;
str = masked_user_access_begin(str);
str = masked_user_read_access_begin(str);
retval = do_strnlen_user(str, count, count);
user_read_access_end();
return retval;